Many European cooks who come to the United States ask the same two questions. "Why are leeks so expensive?" and "What happens to the scallop roe?" The answer to the first is easy: the price of leeks is high because they aren't used in quantity except for an occasional batch of vichyssoise.

The second question gets a blank stare, however. Scallop roe? What in the world is scallop roe?

Even cooks living on the North Atlantic seacoast where most of American sea scallops are brought to shore have never seen the roe, which comes attached to each scallop during the spawning season (loosely, the time from May to November). These bright coral crescents, about the size and shape of a fat little finger, are beginning to surface, however.

Scallop roe is appearing in posh restaurants, usually when the menu is in the charge of a European-trained chef who has included it as a matter of course. Scallop roe comes from France or Belgium while the American roe is tossed to the seagulls as a matter of course.

"Ten years ago, monkfish tails were in a similar situation," said Paul Earl, marketing director for the National Marine Fisheries Service in Gloucester, Mass. "You couldn't give them away. Only ethnic cooks knew what they were, and the crew of a fishing vessel could make a little extra money by saving the monkfish angler fish, lotte and selling it when they got to shore. Now the demand is unbelievable on both sides of the Atlantic."

In January a rumor was going around New England that sea scallop roe would be sold with scallops in American fish markets by summertime. Summer came and none appeared. Any scallop roe that cooks saw was still imported.

A select few diners experience the entire scallop. In Portsmouth, N.H., the recreational divers know about beds of the large scallops that are close to shore. Where remains a secret, but they plunge down, harvest a scallop or two, and eat them right out of the shell when they get to shore. Do they eat the roe, too, or do they carry it home in their specimen bags to have for breakfast with their scrambled eggs?

One fish market owner in Maine, who shall remain nameless for legal reasons, deals in the entire scallop whenever he is lucky enough to get it. Maine protects the inshore scallops from May to November -- yes, yes, the very months for roe.

"The Maine scallop is as big as dinner plates," the fish market owner said, "and I have a Japanese customer in California who wants the entire thing -- shell, roe, viscera, everything. But the only way I can get them is illegally.

"The fishermen who bring them in are pirates -- characters -- the last of their kind. They go out there in the dark and drag for scallops. Then they come around to my back door and I buy them for cash, which they take to the sleaziest bar in town and drink for the rest of the day. I don't know when they sleep."

While covering a story on the Isle of Shoals, eight miles off the coast on the Maine-New Hampshire border, where Cornell and the University of New Hampshire conduct their summer marine program, I saw my first entire, large scallop. The school is given special permission to collect whatever marine life it needs.

So that sunny, crisp day, one lone scallop was brought ashore by a diver in a wet suit (water temperature that week was 56 degrees). It was enormous and when the instructor opened it up, there was an adductor muscle the size of a big marshmallow and a deep coral crescent of roe the size of Arnold Schwarzenegger's little finger.

Later during a cooking demonstration, the chef cut out that one sea scallop and added it to the legal supply he'd brought along. But he treated the roe like the 20 carat, diamond-studded wonder that it was -- poaching it in white wine and reducing the liquid for a sauce. We got this tiny little taste of the scallop roe, but could see the possibilities. It had turned pale pink as some of the dark red salmon species do when cooked.

This year scallop supplies are down -- way down. It's just common sense to feel that the shuckers would begin to save the roe, which amounts to about 50 percent of the edible weight.

In New Bedford, Mass., where most of the Atlantic scallops are sold at auction, Jim Costakes, who owns Seafood Producer's Associaton, has been working on the problem. Five years ago he got a federal grant to test the realities. Finally he had a predictable supply of scallop roe and took it to European markets, where they turned him down flat. Too expensive, they said. Its reception in American markets was even more questionable at any price.

He is still working on it. "It would be good for everybody, but scallopers are proud of their shucking speed and getting out the roe in one piece slows them down."

Earl says that the men are working in the cold and the wet while the boat is bouncing around. "In Europe, the catch is brought in and the shucking is done on shore, making conditions more comfortable."

Time is also a factor. American scallop boats are at sea from eight to 15 days, which makes it impossible to bring back the entire animal. Unlike clams and oysters, the scallop gapes when it is out of water, losing that life-sustaining supply of sea water. It would be dead long before it got to shore.

Bay scallops also have roe, but it appears in the summer when it is illegal to catch them.

Karen Alence, a scalloper and owner of Nantucket I-Ray Seafoods on Nantucket, said, "Anyone who has shucked bay scallops (which are brought to shore daily) has probably entertained the same thought of doing something with the rest of it, which makes up two-thirds of its weight."

So she got a grant and spent an entire season selling the concept of "scallop bellies" as well as the whole scallop.

Years ago Nantucket restaurants served deep-fat-fried scallop bellies, which are similar to fried soft-shell clams, and called them "scallop rings." But they only found the customers enthusiastic when they were freebies served with drinks. On the menu (under any name) they were spurned.

"Whenever I was in a place with European or oriental employes, they would ask for a supply to bring home to their families," Alence said, "reacting as through someone in the United States finally knew that the entire scallop was good to eat."

When Alence took the whole scallop to French chefs in New York, they were receptive, but asked her to bring them back with ripened roe. Unlike those Maine pirates, she is a staunch preservationist and graciously declined.

At any rate, remember the monkfish and keep your eyes open. The day of American scallop roe could come. In the meantime, more to the point, are these recipes for scallops -- without the roe: SEA SCALLOP STEW (6 servings)

1 cup clam juice

1 cup dry white wine

3 tablespoons minced parsley

1/4 teaspoon dried rosemary

1 bay leaf

1/4 teaspoon nutmeg

2 pounds ocean scallops, picked over and halved if very large

4 tablespoons butter

1 pound mushrooms, stems trimmed and caps thickly sliced

2 large scallions, thinly sliced, including some green

3 tablespoons flour

3 tablespoons dry sherry

Rice for serving

In a saucepan, combine the clam juice, wine, parsley, rosemary, bay leaf and nutmeg. Bring to a boil and simmer gently for 10 minutes. Add scallops and continue to simmer until firm for 5 to 8 minutes (depending on size of scallops.) Drain to stop cooking, reserving the poaching liquid.

In a 10-inch skillet, heat butter, and when foaming subsides add mushrooms. Saute' quickly on high heat, tossing often until they are lightly browned, about 5 minutes. Add sliced scallions and cook 30 seconds. Sprinkle flour over contents of skillet and cook for 1 more minute, stirring constantly. Add sherry, poaching liquid and scallops. Reheat and simmer gently until sauce has slightly thickened, 2 to 3 minutes. Serve over rice. BAY SCALLOPS WITH LINGUINE (4 servings)

12 ounces linguine

3 tablespoons butter

2 tablespoons olive oil

1 medium onion, finely chopped

1 clove garlic, minced

1 large tomato, peeled, seeded and chopped (or substitute 1 cup drained, chopped, canned tomatoes)

1 pound bay scallops

1/2 cup dry white wine

1/4 cup minced parsley

Salt and pepper to taste

Bring plenty of salted water to a boil. Add linguine and cook for the least amount of time suggested on the box.

Heat butter and oil in a 10-inch skillet. Add onion and garlic and saute' for 3 to 4 minutes until soft but not brown. Add chopped tomato and scallops and continue to saute' for 3 more minutes or until the scallops are firm. Add wine, bring to a boil and remove skillet from heat. Stir in the parsley, and salt and pepper to taste. Drain linguine and place in a warm serving bowl. Top with scallop sauce and toss at the table.

Note: If the linguine finishes cooking before the scallops are done, drain all but 2 to 3 cups of the water and let it wait at the back of the stove.