NO ONE knows the origin of chowder. Some claim a Breton farmer introduced the Pilgrims to the chaudiere (literally, stewpot), which the New England tongue promptly translated as chowdah. Certain factions disagree about whether the Indians taught us how to make it or we taught them.

Then there is the spontaneous generation theory, which holds that a version of the creamy fish-and-potato stew has emerged in nearly every coastal community. Whatever its orgins, a steaming bowl of chowder is one of winter's major consolations. It remains an ingenious solution to the recurring problem of how to eat and keep warm on a slim budget.

The Pilgrims solved the problem of limited resources by layering the few ingredients available to them -- cod or clams, common crackers, milk and salt pork -- in a large stewpot and letting it simmer. The simplicity of this basic recipe lends itself to experimentation, and the years have spawned thousands of interpretations. (Let us end the debate about Manhattan Clam Chowder here and now. "The Joy of Cooking" defines chowder as a thick stew made with milk. If your cultural heritage demands that you combine tomato paste and clams, you'll have to subscribe to a Manhattan newspaper.)

I have only two cardinal rules for preparing chowder: (1) do not flavor it with tomato or thicken it with flour, and (2) make a double batch so there'll be something to eat on the second day. All chowders taste better after a day in the refrigerator and none can survive the initial onslaught of family and friends crazed by the aroma of salt pork and sauteed onion. (For this reason, it is a bad idea to prepare chowder in areas of the wilderness known to harbor bears: The scent has been known to draw them from six miles away. If, on the other hand, you want to be the first in your neighborhood to spot the New England coyote, cooking chowder over an open fire is probably the best lure.)

If you follow the cardinal rules, however, the variations are endless: Chowders can be made with oysters, salmon, mussels, scallops, chicken, celery, corn and even lima beans. Some people use shrimp and lobster in chowders, which seems a waste to me. The basic chowders are still clam, fish and corn. Master these and you can face the longest winter.

My grandmother makes the best fish chowder in the world. The ingredients are constant (do not, ever, mix fish and clams), but the proportions are very flexible -- in fact, the original Fanny Farmer Boston Cooking School recipe calls for 10 cups of potatoes for three pounds of fish. Most young children would prefer it this way; most greedy adults would lobby for the reverse.

No matter what proportions you use, the perfect chowder depends on the quality of the stock, the freshness of the fish and the salt pork and the slight undercooking of the potatoes.

In making the stock, make sure fish is thoroughly cleaned and gills are removed, as these give an off-taste. Add only enough water to barely cover the fish. Unlike meat stocks, fish stocks do not improve with additional stewing after the first halfhour. If the stock is too weak, you can add bottled clam juice, but the flavor won't be as good. Be wary of using frozen prepared fish stock: Many are either too peppery or too bland. (Some are both.)

Buy the freshest fish you can and use only non-oily white-fleshed fish. Even rockfish, which crops up in many chowders around here, is a little too fatty. Do not overcook the fish -- when first removed from the stock pot, it should still be slightly translucent. Add it to the final chowder in chunks as large as possible and minimize stirring, as the fish breaks up easily.

In selecting salt pork, try to find a piece that is soft, which means it is fresher and more recently salted.

Undercook the potatoes so they remain firm through the second day. GRANDMA HARDEN'S FISH CHOWDER 4 to 5 pounds whole white fish (haddock, cod, sole, hake), cleaned and with gills removed; or 1 to 2 large fish frameds plus about 1 1/2 pounds fillets* Bay leaf Several peppercorns 8 ounces salt pork 5 medium onions, sliced thin 6 medium potatoes, diced Pinch of thyme White pepper Salt 2 to 4 cups whole milk 2 cups heavy cream Common crackers

In a large stewpot, barely cover the fish with water and simmer gently with bay leaf and peppercorns for 10 minutes or until flesh can be removed from bones. Separate fish from bones and set aside. Return bones and head to pot for another 20 minutes. Skim froth as necessary. Strain fish broth and return to pot. Meanwhile, drop salt pork in boiling water for 3 minutes. Remove from heat, dry, remove rind, and dice in 1/2-inch cubes. Saute pork cubes until crisp and toasty brown. Remove and drain.

Saute onions very slowly in remaining fat (at this point, you should probably also bar the kitchen door). When the onions are limp and golden, mix them, the potatoes and the pork cracklings in the fish broth, adding water to cover if necessary. After about 10 minutes, add the fish, thyme, pepper and salt. You won't need much, as the salt pork provides quite a bit. Heat milk and cream separately, then add to the pot. Let the chowder heat gently for 5 to 30 minutes, but do not boil. Serve in big soup bowls with oyster crackers or common crackers, which are large, bland, and traditional. Settle down for long winter's nap.

*Note: Fish frames are what's left when cod or haddock are filleted. A 20-pound cod frame provides a lot of meat, for a bargain price, but you'll have to hack it up to fit in the pot.

To make the clam chowder, substitute about 1 1/2 quarts of clams for the fish. Rinse clams several times, then steam in about 4 cups water. Ironically, New England clam chowder is the best use for Maryland clams, which are larger, mushier, and generally less well-regarded than New England clams. The steaming water becomes the stock, which, again, can be fortified with clam juice if necessary. Shuck the clams and separate the tough necks from the soft part of the clam. Chop the pieces into largish chunks. From herein, the recipe is identical to that for fish chowder, except that you may wish to saute the clam necks briefly with the onions. Again, be careful not to overcook the fish.

Corn chowder has two major advantages over fish or clam chowder: It is very cheap and much easier to prepare. Simply substitute about 20 ounces of frozen corn (or 2 cups fresh corn if the season is right and you're feeling ambitious) for the fish and about 5 cups chicken stock for fish broth. Saute the salt pork and onions as usual. You can also add a cup of finely diced celery and 1/2 cup of finely diced green pepper for extra flavor. Cook with potatoes and corn, with the sauteed ingredients, in the chicken stock. Add milk and cream and accept praises from all around.