Before you smirk at the flame-powered copper pot and pile of day-old bread, you should be informed: Fondue is back. Fondue restaurants are opening around town and newlyweds are again receiving pots specifically designed to melt cheese. For those who have forgotten how or who never had it right in the first place, here are a few fondue facts.

Rule No. 1, which may save many a relationship, is that lumpy fondue is rarely the fault of the cook; it's the cheese. According to "The New Doubleday Cookbook" (Doubleday, 1985), if the cheese is poorly aged or not Swiss gruye`re or emmenthaler, it may never melt smoothly. Gruye`re, incidently, is the one with the small holes and nutty flavor while emmenthaler sports larger holes and a milder bite.

But from Martha Stewart in "Entertaining" (Clarkson N. Potter, 1982), however, comes this variation: Mix 1 pound grated sharp cheddar with 1 cup beer in a fondue pot or crock pot and heat slowly, stirring frequently, until melted. Add 1 teaspoon paprika, a pinch cayenne, 1 tablespoon mustard, salt and pepper to taste and serve.

Whatever cheese you choose, however, watch the burner. Too intense heat might cause the cheese to string. And use acidic wine if possible, like a soave, sauvignon blanc or inexpensive chardonnay.

To avoid dribbling Switzerland's national dish on the tablecloth, some suggest swirling the fondue quickly around the bread on the fork. This catches the drips and helps it cool off. And according to tradition if you lose your hunk of bread in the bubbling cheese, you must forfeit something, often a kiss. Of course, with whom you are supping has a lot to do with your finesse.

Below are two recipes for the traditional cheese fondue. The second one, created by Barbara Kafka, offers a new concept in fondue making, microwaving and reheating.

Express Lane: gruye`re cheese, emmenthaler cheese, cornstarch, white wine, garlic, kirsch, nutmeg, French or Italian bread, caraway seeds (optional)

FONDUE NEUCHATELOISE (4 to 6 servings)

1/2 pound imported Swiss gruye`re cheese, coarsely grated (about 2 cups)

1/2 pound imported Swiss emmenthaler cheese, coarsely grated (about 2 cups)

1 tablespoon cornstarch

2 cups dry white wine, preferably neuchatel

1 medium-sized garlic clove, peeled and bruised with the flat of a knife

2 tablespoons imported kirsch

1/8 teaspoon nutmeg, preferably freshly grated

1/8 teaspoon salt

Freshly ground black pepper

1 large loaf French or Italian bread with the crust left on, cut into 1-inch cubes

In a large bowl, toss together the cheeses and cornstarch until thoroughly combined. Pour the wine into a 2-quart fondue dish (or any 2-quart, flame-proof, enameled casserole), drop in the garlic, and bring to a boil over high heat. Let the wine boil briskly for 1 or 2 minutes. Discard the garlic. Lower the heat so the wine barely simmers. While stirring constantly with a table fork, add the cheese mixture a handful at a time, letting each handful melt before adding another. When the fondue is creamy and smooth, stir in the kirsch, nutmeg, salt and a few grindings of black pepper, and taste for seasoning.

To serve, place the fondue dish or casserole over an alcohol or gas table burner in the center of the dining table, regulating the heat so the fondue barely simmers. Set a basket full of the bread cubes alongside the fondue. Traditionally, each diner spears a cube of bread on a fork (preferably a long-handled fondue fork), swirls the bread about in the fondue until it is thoroughly coated, then eats it immediately.

From "A Quintet of Cuisines," by Michael and Frances Field (Time-Life Books, 1983) BARBARA KAFKA'S MICROWAVE FONDUE (Makes 1 cup to serve 4 as a light meal or first course)

1 cup dry white wine

2 cloves garlic, smashed and peeled

1/2 pound Swiss gruye`re or emmenthaler cheese

2 teaspoons kirsch

1 loaf country-style Swiss, Italian or sourdough bread, cut in 1 1/2-inch cubes, each with some crust

Toasted caraway seeds to dip the cheese-covered chunks of bread in (optional)

Put white wine and garlic in a 1-quart souffle' dish. Cook, uncovered, at 100 percent for 5 minutes.

Place cheese in the work bowl of a food processor. Pour in hot wine. Process for 2 minutes.

Return mixture to souffle' dish. Cook, uncovered, at 100 percent for 2 minutes; stir; cook for 2 minutes longer.

Put souffle' dish on heat source at the table. Stir in kirsch. Serve with bread chunks.

To reheat fondue: Fondue can be made ahead without risk, even a day ahead. The cooled fondue will congeal into a rubbery chunk covered with liquid. Fear not; the microwave is here. Let fondue come to room temperature in the souffle' dish. Cook, uncovered, at 100 percent for 4 minutes. Remove from oven; whisk vigorously and serve. From "Microwave Gourmet," by Barbara Kafka (William Morrow and Co. Inc., 1987)