THREE WEEKS ago I ordered chayote for my local food cooperative. By afternoon I had received 10 phone calls. "What is this strange looking vegetable?" "Chayote," I calmly replied. "Treat it like eggplant or zucchini." My answer did not help the less than enthusiastic members one bit.

Chayote (pronounced cha, not ka), or vegetable pear, is the Spanish name for cho-cho (English) or christophene (French.) It is a member of the cucumbr family, is deeply ribbed, with a greenish-white rind and a soft, edible seed inside. Once a principle food of the Aztecs and the Mayans, chayote is thought to be indigenous to Mexico. Today the vegetable is cultivated in tropical regions throughout the world, especially the Dominican Republic, Puerto Rico and even California and Florida. It tastes rather like summer squash but is more delicate.

Ever since I first tasted chayote in the Carribean I have been on the watch for the vegetable. From Washington's Latin American community I have gleaned many recipes including a now popular dish in my family -- chayote sandwiches stuffed with cheese.

The Bethesday Avenue Food Cooperative now features it on their "life line," to introduce customers to new vegetables. Their pitch is that chayote is just as versatile as zucchini, and it is low in starch.

It is available year-round in all Latin American food stores as well as Magruder's Safeway International and many local natural food stores. It costs about 65 cents a pound.

Curiously enough, only La Fonda, of all the Hispanic restraunts in Washington, even lists it on the menu. At this Mexican restauant it is stuffed or served rataouille style with onions, tomato and green peppers.

It was not until I met an unlikely chayote, source, Fritz Blumberg, Alrington Hyat House's Germany chef, an unlikely chayote source, that I learned more fully about using it. Blumberg became acquainted with the vegetable working in a hotel in the Dominican Republic. "In the hot climate I had to experiment with what I had." Experiment Blumberg did. Soon highly perishable cantalopes replaced by cold chayote boiled and served with prosciutto. Blumberg found that chayotes hold their shape better than most cooked vegetables. Boiled chayote worked its way into salads, ousting cucumbers which became mushy. On hot steam tables chayote took the place of yellow squash and zucchini.

How to pick chayotes? Look for the smallest possible, a little larger than the size of a large fist. The vegetable should weigh between 3/4 and 1 pound and be light green in color without spots. The refrigeration life is quite long, two to three weeks. It keeps fairly well if merely surrounded by a damp cloth and placed in a dark place. Although Blumberg uses a pressure cooker when making most of his dishes with chayote, the vegetable can be easily halved and boiled for about 50 minutes. The chayotes used here have a great deal of water in them, making draining essential. After this preliminary step the chayote can be diced and dotted with butter, salt and pepper, served cold with a vinaigrette sauce, added to sauteed onions and potatoes and covered with a bechamel sauce or baked and stuffed with meat, fish or rice. Taking Blumberg's lead I recently stretched an expensive meat and artichoke dish with chayote.

Having tasted and tested and my way through many chayote recipes, I was able to report back to the members of my co-op. Before I even started telephoning, one enthusiast told my answering machine, "Thank you for introducing me to chayote. My family loves it and now I'll buy it on my own." CHAYOTE RELLENO CON CAMARONES Mery de Tajada's Panamian Stuffed Chayote with Shrimp (8 to 10 servings as a appetizer) 5 chayotes (3/4-1 pound each) cut in half 2 chicken bouillon cubes 1 pound medium shrimp, cooked, peeled and deveined 1 medium sliced onion 1 sliced green pepper 1 clove garlic, minced Pinch of pepper Crushed hot pepper to taste 2 tablespoons fresh coriander 1/2 diced celery stick 1 grated carrot 2 tablespoons vegetable oil 2/3 cup tomato sauce with mushrooms Salt to taste 1/4 pound grated Spanish or Monterey Jack cheese

Boil the chayote halves in water with bouillon cubes until soft, about 40-50 minutes. Cool. Carefully remove the pithy core, almond-like seed and pulp without destroying the shell. Mash and drain well. Set the shells upside down to drain.

Meanwhile prepare the shrimps.

Combine the onion, green pepper, garlic, pepper, hot pepper, coriander, celery and carrot. Saute in the oil until onion is golden. Add the chayote, tomato sauce and salt to taste. Mix well. Adjust seasonings.

Spoon the mixture into the chayote skins. Sprinkle with grated cheese. Transfer to greased low baking dish. Bake in 350 degree oven for 20 minutes. FRITZ BLUMBERG'S CHAYOTE SALAD (4 to 6 servings) 3 chayotes (about 3/4-1 pound each) Salt and pepper to taste 6 scallions, chopped Oil Vinegar

Boil the chayotes for 20 minutes in a pressure cooker of 60 minutes in water. Cool, peel and dice into 1/2 inch cubes.

Season with salt and pepper and mix with the diced scallions, using both the white and green parts. Dress with oil and vinegar.

Note: You can also add diced fresh tomatoes, cold, boiled potatoes. This dish is also delicious with a roquefort dressing spiked with grated pineapple. SAINT MAARTEN'S BOILED CHRISTOPHENE (6 to 8 servings) 2 christophene (3/4 pound each) Boiling salted water 2 tablespoons butter Salt and pepper to taste

Peel the christophene, dice and boil in salted water about 20 minutes or until tender. Drain. Dot with butter and season with salt and pepper. Serve at once. ELIA REYES' EL SALVADOREAN CHAYOTE WITH CHEESE SANDWICHES (6 to 8 servings) 2 chayotes (about 3/4-1 pound each) Boiling salted water 1/2 pound Spanish cheese 4 eggs Oil for frying

Peel the chayotes and make 1/2 inch circular slices, Place in boiling salted water, cooking until tender, about 20 minutes. Remove from water and drain.

When chayotes are cool slice the cheese aoub 1/8 inch thick and make sandwiches using two slices of chayotes as the bread. Beat the eggs well and coat the chayote sandwiches.

Heat oil in frying pan and fry sandwiches on each side until golden. Serve at once. MEXICAN CAHYOTES RELLENOS (Stuffed Vegetable Pears with Cheese) (6 servings) 3 chayotes 2 teaspoons salt Boiling water to cover 2 heaping tablespoons butter 1/2 medium onion, finely chopped 2 cloves garlic, peeled and finely chopped 4 eggs, well beaten with salt and pepper 6 ounces farmer or drained cottage cheese, crumbled 12 small strips Muenster or mild cheddar cheese 12 tablespoons thick sour cream

Place the whole chayotes and the salt in boiling water and cook until tender, about one hour.

Drain and let cool. Peel, then cut in half, remove the pithy core and almond-like seed. Scoop out the flesh carefully, leaving a 1/8 inch outside core. Mash the inside flesh well and leave to drain in a colander for a few minutes. Place the shells upside down to drain.

In a small frying pan melt the butter and cook the onion and garlic gently, without browing until they are soft.

Add the eggs and stir as you would for scrambled egs until they are just set. Add the mashed chayote flesh and let the mixture dry out a little for a minute or so over a low flame.

Stir the framer cheese into the mixture and stuff the reserved chayote shells. Place in an ovenproof dish. Place the cheese strips and sour cream on top of the filling and heat in a 400 degree oven for about 15 minutes.

Note: This can be served topped with tomato sauce instead of cheese and sour cream.