GEORGE Markos has lived in the United States since 1965, but he remembers the Easter celebrations in his native Crete as if they were yesterday.

In Crete, they block off the streets before the Resurrection Mass on Easter eve, he said. After the priest chants, "Christ is risen," the people walk home from church carrying lighted candles. It is springtime. The lambs have been slaughtered, and the countryside is turning green. But to assure a good harvest, age-old observances must be carried out.

"Everyone is in a good mood," Markos said. The Lenten fasting is over, and the feasting begins: A special bread is served, decorated with five red eggs arranged in the shape of a cross. Then comes mageritsa, a traditional soup including lamb hearts, liver, intestines and fresh dill.

No one goes to bed hungry, but the midnight repast is just a light snack compared with the spread laid out on Easter Sunday.

Markos, 34, co-owner of the Akropol restaurant in Falls Church and a member of St. Katherine's Greek Orthodox Church, usually spends Easter barbecuing one or more whole lambs for family members who congregate in his back yard; this year he's moving the celebration to his restaurant and opening it to the public. That means not one lamb but 40.

Family members recently visited a farm in Winchester, Va., where they selected young lambs from a large herd. Markos' father, 70, carves all the restaurant's meat, and he was in charge of the operation, carefully saving the entrails necessary in preparation of the ritual soup. Many of the parts, such as the intestines, are not available from commercial butchers. They've borrowed extra spits from local churches.

Markos said most of his preparations are finished. Salads of eggplant and caviar will be served as appetizers. There will be a variety of Greek breads, including pita and egg bread, and Greek salad: mounds of lettuce ornamented with black olives, white slices of feta cheese, sprinkled with oregano and doused with olive oil. After that, red eggs, scallions, relishes and a variety of sauces, including yogurt sauce. For weeks his family has been baking Easter cookies, such as the snowy, confectioners' sugar-coated kourabiethes. All will be served on a long buffet inside the tent.

Lamb is a wonderful entre'e for large crowds during any of the fine-weather months. However, Markos is also roasting a third, traditional appetizer, kokoretsi, that requires ingredients not commercially available. It is a delicacy he insists is necessary for continued youth, vigor and good luck in the coming year.

Kokoretsi consists of lamb liver and heart--as well as the lungs, kidneys and sweetbreads, if you have them. Each piece is skewered individually and wrapped in a delicate membrane surrounding the lamb's internal organs. The membrane is encased by intestines, and the whole package is securely fastened to the skewer with fine wire. Cooking time is 1 1/2 to 2 hours over a hot coal or wood fire. The dish must be frequently basted with retsina, the white table wine flavored with resin.

"Pour yourself a glass of retsina while you're watching the fire," Markos says, "then carve a thin slice of kokoretsi, and you'll have the best appetizer ever."

Markos' Easter feast, will be held from noon until midnight Sunday at 132 W. Borad St., Falls Church. Reservations are necessary; they may be made by calling (703) 532-2772. Groups of 18 to 20 may order a whole lamb, with accompaniments, for $260. Half a lamb is $130, and it will serve 10. Five or six people can buy a quarter of a lamb for $65, and individuals will be charged $14.95 for a complete meal. Children will be served at no charge. HOW TO COOK WHOLE LAMB

During the Easter season spring lambs, 20 to 40 pounds, dressed weight, are available from Bay State Beef, 1431 Okie St., NE (269-1100). At other times, they may be ordered two weeks in advance. The price is $3.75 to $5.50 per pound, depending on the size of the lamb. You pay more per pound for smaller carcasses. Markos advises buying 35 pounds to feed 15 to 18 people.

Large, heavy-duty electric rotisseries may be rented for about $45 a day. One standard model includes a rack with a steel trough for the coals, a skewer on which there are two sets of U-shaped prongs that to hold the meat in place, and a motor. The whole lamb comes with the head--considered a delicacy by the Greeks--as well as the heart and liver. These may be used for soups. Unless you plan to pick up the lamb on the day of your party, don't forget to clear enough space in your refrigerator to store the carcass until you're ready to cook it.

Some rotisseries have a steel trough to hold the coals. Others operate over a fire built on the ground. Either way, plan on starting a charcoal fire at least one hour before cooking the meat. A wood fire will need two to three hours to burn down to a good bed of coals. About 25 to 35 pounds of charcoal is enough for one lamb. Markos prefers to cook over a wood fire. He says the smoke adds flavor to the meat.

It's hard to estimate how much wood you'll need, as the rate of combustion varies depending on the variety and age of the wood. If you don't have enough wood on hand, try adding flavorful hickory or apple chips to a coal fire.

Now fasten the meat on the skewer. Some skewers have removable prongs to hold the meat. If yours doesn't, you'll also need a green stick to spread the back legs. Remove the prongs from one end of the skewer, and insert the skewer through the tale end, sliding it under the backbone until it emerges through the head. The front prong should hold the head in place. Fasten the back legs to the other set of prongs so they are fanned out, using a green stick, if necessary, to hold them in place. Use fine wire to secure the green stick. Then tie the ends of the front legs to the skewer with fine wire. Use more wire to truss the belly closed. If desired, insert a meat thermometer in the thickest part of the leg.

Plan your schedule. A 35-pound lamb will probably take between five or six hours to roast. Lamb is done when it reaches an internal temperature of 175 to 185 degrees--but by then it's pretty well done. If you like your meat rare, you might want to take it off the fire before it gets that hot inside. Another test for doneness is to pierce the leg with a fork. The meat is done when the juices run clear. Don't forget to let the lamb sit for 20 minutes before carving.

Baste the lamb regularly with a sauce of three cups olive oil, one cup lemon juice, one clove minced garlic, or more to taste, and one tablespoon oregano. Tie cheesecloth onto a stick to apply the basting sauce. Arrange the rotisserie so the meat turns about 6 inches above the coals. Add more coal or wood as necessary to maintain a hot, even fire. Douse the fire with water should it flare up--you don't want the meat to burn. EGGPLANT SALAD (10 to 12 servings) 3 large eggplants 1 to 1 1/2 cups olive oil 1 cup milk Juice of 2 lemons 1/2 cup feta cheese, mashed and beaten smooth 1 clove garlic, peeled and minced Salt and pepper Fresh parsley, chopped Pita bread or romaine lettuce

Pierce the eggplant with a fork several times and bake for 1 hour at 350 degrees. Cool and peel, scraping the skins with a knife to remove all remaining flesh. Finely chop the eggplant into 1/4-inch pieces.

Place eggplant in a large bowl. Add a little bit of olive oil, then milk, alternately stirring constantly with a wooden spoon. The eggplant will absorb all the liquid. Add lemon juice, feta, minced garlic, salt and pepper to taste. Place in a serving bowl, garnish with fresh, chopped parsley. Serve with warm pita or atop individual servings of romaine lettuce. SATZIKI (Yogurt sauce for lamb) (6 servings) 6 large cloves garlic, peeled and minced 1/4 cup olive oil 2 tablespoons white wine vinegar 1/4 teaspoon salt Dash black pepper 2 cups plain yogurt 1 large cucumber, peeled and shredded

Place the minced garlic in a bowl and mash with oil, vinegar, salt and pepper. Add yogurt a little at a time beating well. Fold in cucumber, including seeds. Serve as an accompaniment with lamb. TARAMA SALAD 1/2 cup tarama (Greek caviar, available in jars in Greek import stores) 1 pound white potatoes, about 2 large, boiled, peeled and mashed 1 to 1 1/2 cups olive oil Juice of 1 lemon 2 tablespoons white wine vinegar Fresh parsley, chopped Pita, melba toast or greek bread

Place the tarama in a large bowl. Add the mashed potatoes alternately with the olive oil, a little at a time, stirring well after each addition.

Season with lemon and vinegar and place in a serving bowl. Garnish with fresh, chopped parsley. Serve as an appetizer with pita, greek bread or melba toast. KOURABIETHES (Greek Easter cookies) (Makes 5 dozen) 2 cups unsalted butter, at room temperature 1/2 cup sifted confectioners' sugar 2 egg yolks 1 teaspoon baking powder 5 to 6 cups sifted all purpose flour or 5 cups sifted all purpose flour and 1 cup finely pulverized toasted almonds 2 teaspoons vanilla 1 tablespoon milk Sifted confectioners' sugar

In the large bowl of an electric mixer, cream butter until fluffy. Add sugar and beat well, then mix in the egg yolks. Sift baking powder with the flour and add to the dough, a little at a time, mixing well after each addition, just until the dough forms a ball. Add the nuts if desired, but in that case you'll need a little less flour. Stir in the vanilla and milk.

Flour your hands and roll the dough into 1-inch balls. Place on a greased cookie sheet and bake for 15 to 20 minutes or until lightly browned. Cool, and roll in sifted confectioners' sugar.