A student sitting in on one of cooking instructor Marcia Fox's classes explained why she signed up for an evening of grilling, poaching, saute'ing and baking fish: "I've lived on the East Coast all my life and I've only had fish in restaurants." The student didn't know how to prepare fish, she admitted, and so avoided making it altogether.

Such concern is common among a lot of cooks. In reality, though, preparing a piece of fresh fish is about as difficult as making a hamburger.

So why the anxiety? "Most people overcook fish," explains Fox, founder of World of Cuisine cooking school in Alexandria. "They don't know how to judge when it's done." Unlike with meat and poultry, she says, determining that point at which fish is done involves a combination of touching and looking. The problem is not helped by the fact that different fish look different when done, even when prepared the same way, adds the instructor.

One simple way to avoid overcooking is to remove fish from the pan as soon as it's done -- even if the pan is removed from the heat source, advises Fox, it continues to cook. And as far as technique is concerned, she encourages first timers to try poaching fish, a method which she believes "offers cooks the most control over how done it is."

Fox's fish accompaniments range from creme fraiche and pommery mustard (slathered on grilled salmon steaks) to an assertive coating of almonds, soy sauce and red pepper (on baked orange ruffy). Her choice of garnishes depends on the type of fish she's serving: Varieties such as salmon, swordfish and tuna lend themselves well to robust flavors. Sole, flounder and haddock, on the other hand, require more delicate treatments.

Fox, who teaches a number of different cooking classes year round, is scheduling her next fish course Feb. 19. The fee is $35. Call 998-3079 for more information.

Meanwhile, here's an elegant and very simple dish that even first-time fish cooks should have no problem executing. Fox suggests serving this with a colorful side dish of spinach pasta, or a saute' of broccoli and red peppers.

Express Lane list: swordfish, bread, swiss cheese, onion, lemon, cognac, almonds

MARCIA FOX'S SWORDFISH STEAKS WITH CHEESE AND COGNAC (4 servings)

1/2 cup (1 stick) butter, melted

4 8-ounce swordfish steaks, about 3/4-inch thick

Salt

2 slices good quality white bread

3 ounces Swiss cheese, grated

2 teaspoons grated onion

Zest of 1 lemon

1 tablespoon lemon juice

About 4 tablespoons cognac

1/2 cup slivered almonds

Butter a flame-proof dish and arrange steaks over. Season with salt. Tear bread into crumbs and combine with cheese, onion, lemon zest and lemon juice. Spread over fish and bake in a 375-degree oven 20 minutes or until barely cooked.

Remove fish from oven. Pour cognac around the bottom of the pan (not on the fish). Sprinkle almonds over fish. Return dish to oven for 5 minutes. If desired, remove, and while the container is still very hot, place on table, pour over another 2 to 3 tablespoons brandy and light.