Julia Child was coming to dinner, so it was with some trepidation that I had prepared a rather grand feast. She walked in, saw the terrine on the table, said "Goodness that looks good!" and cut herself a slice. The evening was a success.

Terrines do have an instant, welcoming appeal that says "Try me." Perhaps it's no coincidence that the name comes from terre, meaning earth. Any mixture cooked in a terrine mold earns the name, from time-honored combinations of pork, ham, liver and truffles to new-style creations of fish and vegetables. Terrines are even appearing at dessert.

I've chosen these three terrines as the answer for all kinds of fall entertaining. The flavors -- fish, ham and vegetables -- marry well so they can be served together as the foundation for a cold buffet, needing only bread, salad, cheese and fruit to complete a full meal. You could slice one (or all of them) to serve on toast for canape's, and alone each makes a versatile appetizer for dinner or a luncheon main course.

A good terrine is moist, light but firm, and with a subtle blend of flavors. All these qualities are developed by cooking in a heavy mold; porcelain and enameled cast iron have joined earthenware as mold materials, many of them brilliantly colored or painted with pretty designs. If you do not have a mold, a terrine can always be baked in a loaf pan, preferably made of glass. A tight lid helps seal in juices, though foil will do instead, and I favor a long loaf shape, which cooks evenly and slices neatly for serving.

A reliable recipe does the rest, for it's important to achieve just the right balance of lean meat, fat or cream (vital for richness), eggs for binding, and appropriate herbs and spices. You'll find a food processor or blender a boon in pure'eing smooth mixtures of fish and vegetables. The amount of seasoning for a terrine varies very much with the ingredients, so taste the mixture carefully before cooking, even if, as with pork, you have to fry a small piece to try.

Lastly, a terrine should be aged for at least a day and for robust meat and game mixtures, up to a week. If you run a layer of clarified butter on top of the terrine to seal out air, then keeping time is doubled. As it sits, flavors in the terrine blend and mellow so that when it is cut open (at room temperature for maximum enjoyment) the aroma should urge you instantly to consume a generous slice.

With the following recipes, green olive mayonnaise is an important complement to both the fish terrine with caviar and the vegetable terrine, which can be dry without it. If arranging all three terrines on a plate, I'd spoon the mayonnaise next to these two, with a sprig of watercress beside the ham with hazelnuts, which is rich enough to eat alone. TIMETABLE

A cook's delight, the whole of this menu can be prepared days ahead and simply arranged on plates just before serving.

Up to 5 days ahead: Make ham terrine and refrigerate.

Up to 2 days ahead: Make fish terrine and refrigerate. Make vegetable terrine and green olive mayonnaise and store in refrigerator.

Up to 3 hours ahead: Remove terrines and mayonnaise from refrigerator and leave at room temperature. Set the table. Chill the wine.

1 hour before serving: Unmold terrines, slice them and arrange on plates or platters. Add decoration and cover tightly with plastic wrap. Transfer mayonnaise to serving bowl. FISH TERRINE WITH CAVIAR (12 servings as part of this menu; 4 to 6 servings alone)

Sole, whiting, flounder, white fish or catfish are all suitable for this recipe. If the fish has been frozen, add an extra egg white to compensate for moisture.

Butter for mold

1 1/2 pounds white fish fillets

3 egg whites, lightly beaten

Salt and white pepper to taste

Grated nutmeg to taste

1 cup whipping cream or cre me frai che

2-ounce jar red caviar

Green olive mayonnaise (below) or plain mayonnaise for serving

Butter a 1-quart terrine mold or loaf pan, line base with waxed paper and butter the paper.

Trim fish fillets of any skin or bone and cut in strips. Pure'e fish in a processor. Pure'eing constantly, gradually add egg whites. Season with salt, pepper and nutmeg and gradually work in cream. Transfer mixture to a bowl and chill in freezer or over ice, stirring occasionally. Taste it for seasoning.

Mix 1/2 cup mixture with caviar for filling. Spread half remaining terrine mixture in prepared mold. Spread filling down center, leaving 1-inch gaps on each side. Fill mold with rest of mixture, smoothing the top. Press buttered waxed paper on top and add the lid or a foil cover.

For moist, even heat, terrines are cooked in the oven in a water bath. Heat oven to 350 degrees. Set the mold in a roasting pan with at least 2 inches of water. Bring to a boil on top of stove. Cook in oven until terrine is firm to the touch, from 1 to 1 1/4 hours. A skewer inserted in center of mixture for 30 seconds should be hot to touch when withdrawn. Let terrine cool to tepid, then remove lid and set a board or plate with a 2-pound weight on top to press the mixture (a brick is ideal) and let cool. It can be made up to 2 days ahead and kept in the refrigerator.

To finish, unmold terrine and cut in 3/8-inch slices. Arrange slices on a platter or individual plates and spoon mayonnaise at the edge. Serve remaining mayonnaise separately. HAM TERRINE WITH HAZELNUTS (12 servings as part of this menu; 6 to 8 servings alone)

Country ham gives this terrine an excellent flavor, but be sure it is not too salty.

1 1/2 cups shelled hazelnuts

1/2 pound sliced barding fat, or bacon

1 tablespoon butter

1 onion, chopped

1 pound lean pork, cut in 1-inch cubes

1/2 pound pork fat, cut in 1-inch cubes

1/2 pound lean ham, cut in 1-inch cubes

2 eggs, beaten to mix

2 tablespoons brandy

1 teaspoon allspice

1/2 teaspoon nutmeg

Salt and pepper to taste

1/2 pound thick slice of cooked ham, cut in wide strips

1 bay leaf

1/2 teaspoon dried thyme

Toast hazelnuts until brown in a 350-degree oven, 10 to 12 minutes. If necessary, rub them with a cloth to remove skins. Leave oven heated. Line 1 1/2-quart terrine mold or loaf pan with strips of fat or bacon, reserving 2 to 3 for top.

For terrine mixture: Melt butter in a small pan and fry onion until soft but not brown. Work pieces of ground lean and fat pork with ham through fine blade of a grinder into a bowl. Stir in hazelnuts, onion, eggs, brandy, allspice, nutmeg and plenty of pepper. Salt may not be needed, as ham is salty. In a small pan, fry a small piece of mixture and taste for seasoning; it should be quite spicy.

Spread 1/3 of terrine mixture in prepared mold and top with half the ham strips. Add half remaining mixture, top with ham strips and cover with remaining mixture. Lay fat or bacon strips on top and add bay leaf and thyme. Cover mold with lid or foil.

For moist, even heat, cook the terrine in the oven in a water bath. Heat oven to 350-degrees. Tightly cover the mold with lid or foil and set it in a roasting pan with at least 2 inches of water. Bring to a boil on top of stove, then cook in oven until terrine is firm to the touch about 1 1/4 to 1 1/2 hours; a skewer inserted in center of mixture for 30 seconds should be hot to touch when withdrawn. Let terrine cool to tepid, then remove lid and set a board or plate with a 2-pound weight on top to press the mixture (a brick is ideal). Ham terrine can be made up to 5 days ahead and refrigerated.

To serve, let terrine come to room temperature. Unmold it, cut in 1/2-inch slices and arrange on individual plates or a platter. Alternatively, serve terrine in the mold. TRICOLOR VEGETABLE TERRINE (12 servings as part of this menu; 4 to 6 alone)

This terrine is also good served hot with a tomato sauce.

2 pounds fresh spinach

6 eggs

Salt and pepper to taste

Grated nutmeg to taste

1 1/2 pounds carrots, washed

2 tablespoons butter

5 tablespoons whipping cream or cre me frai che

1 pound root celery or turnip, washed

Green olive mayonnaise (below) or plain mayonnaise for serving

Bunch of watercress for garnish

Discard stalks from spinach and wash thoroughly. Put spinach in a large pan, cover and cook, stirring occasionally, until wilted, about 5 minutes. Drain, let cool, then squeeze spinach in your fist to extract all water. Pure'e in a food processor. Add 2 eggs and mix well. Season pure'e with salt, pepper and nutmeg to taste. Alternatively, pure'e spinach and eggs, a little at a time, in a blender.

Grate the carrots. In a saucepan melt half the butter, add carrots with 2 to 3 tablespoons water, salt and pepper. Press a piece of foil on top, cover and cook very gently until carrots are tender, 12 to 15 minutes. Uncover, add half the cream and cook, stirring, until almost all liquid has evaporated. Let cool, then stir in 2 eggs. Taste mixture for seasoning.

Grate the celery or turnip, putting it at once in a saucepan of cold water to prevent discoloration. Bring to a boil, simmer 2 minutes and drain. Note: This removes bitterness. Put back in pan with remaining butter, 2 to 3 tablespoons water, salt and pepper. Cook as for carrots. When cool, stir in remaining 2 eggs and taste.

Butter a 1 1/2-quart terrine mold or loaf pan and line bottom with waxed paper, buttering the paper. Spread spinach mixture in a layer in bottom, add carrot mixture and finish with a layer of celery or turnip mixture.

For moist, even heat, cook the terrine in the oven in a water bath. Heat oven to 350 degrees. Tightly cover the mold with lid or foil and set it in a roasting pan with at least 2 inches of water. Bring to a boil on top of stove, then cook in oven until terrine is firm to the touch for about an hour. A skewer inserted in center of mixture for 30 seconds should be hot to touch when withdrawn. Let terrine cool to tepid, then remove lid and set a board or plate with a 2-pound weight on top to press the mixture (a brick is ideal).

Terrine can be cooked up to 2 days ahead and refrigerated. If serving cold, let it come to room temperature; if serving hot, reheat it in a water bath in a 350-degree oven.

To finish, unmold terrine, cut it in 1/2-inch slices and arrange on a platter or individual plates. Spoon mayonnaise around the edge and decorate with watercress. Serve remaining mayonnaise separately. GREEN OLIVE MAYONNAISE (Makes 1 1/2 cups mayonnaise)

Good with fish and hard-cooked eggs as well as vegetables. For a milder flavor, substitute salad oil for half of the olive oil.

1 cup green olives, drained and pitted

1 clove garlic, crushed

2 egg yolks

Salt and pepper to taste

1/2 teaspoon dijon-style mustard

1 cup olive oil

Juice of 1 lemon, more to taste

If olives are salty, blanch them by boiling in water 3 minutes and draining. Pure'e olives and garlic in a food processor. Add egg yolks, salt, pepper and mustard and work 1 minute. Pure'eing constantly, add oil a teaspoon at a time until mayonnaise is quite thick. Add remaining oil in a slow steady stream, then lemon juice. Taste, adding more lemon juice, salt and pepper if needed. Mayonnaise should be the consistency of sour cream. If necessary, thin it with 2 to 3 tablespoons warm water.

To make olive mayonnaise in a blender, pure'e only half the olives with egg yolks, pure'eing the rest after all oil has been added. If mixture is too thick to churn, add warm water.

Olive mayonnaise can be made 2 days ahead and kept covered in refrigerator. Let it come to room temperature before serving and do not stir when cold or it may separate.

Tip: If mayonnaise separates, keep the curdled mixture. Work an extra egg yolk with 1/2 teaspoon mustard until thick, then slowly add curdled mixture, working constantly.