I put it in the oven and I cooked it and I opened it and no spaghetti. And I cooked it two hours and no spaghetti," wrote one bewildered cook trying to prepare spaghetti squash. It was one of thousands of similar letters Frieda Caplan gets every years from people confronting fruits and vegetables they have never seen before.

Frieda's Finest, a Los Angeles-based wholesaler of produce, has been specializing in "funny foods" for 17 years. When the company began, that category included mushrooms and pineapple. But many of yesterday's unkown edibles are today's staples.

One of Frieda's newest is the slender-stemmed, ivory-colored Japanese enoki mushroom. Unitil the 1860s, they were almost unknown even in Japan, where only northern farmers dined on the exotic fungus. From there, enoki dake made their way to Los Angeles, where they have been grown in the heart of the downtown business district for the last two years.

Recently the mushrooms appeared in Washingtion.

Looking more like a beam sprout with a cap then an ordinary mushroom, the enoki has a somewhat woodsy taste. It can be used in salads or in Chinese dishes, but should be cooked only slightly if at all.

Another of Frieda's surprises is the "large brown turnip" that some Washington consumers have seen in supermarkets lately. It is jicama, widely used in Mexico and well known in southern California a bulbous root of a leguminous plant with a juicy, crisp white flesh of radish /photato consistency.

New vegetables like these are succeeding, according to Caplan's daughter Karen, because "people are being educated to buy fresh. They are very conscious of quality and nutrition. And they like new and different things." Clearly, many do: The business now grosses over $5 million a year, she says, by taking "the things no one else in the wholesale business had time to sell because they didn't come in carloads." (Frieda, From M1>

Karen Caplan believes that you can sell strange foods by showing people how to use them. So all of the packaged produce the company sells comes with purple and white foldover cards listing recipes and information on storing, preparation and nutrition. The cards help in presuading supermarkets to take exotic items, most of which are prepackaged:

"they want to know why they should buy our sugar snap peas when they can buy them in bulk," Karen Caplan says. "And we tell them because consumers won't know what to do with them without the instructions."

That is often true. Sugar snap peas, the newest of the new vegetables, should be eaten shell and all, preferably uncooked. In fact, the shell is the sweetest part. But when they arrived here, many people discarded the pod and cooked the peas. The results aren't bad, but hardly as spectactular as the raw, unadorned sugar snap. And at a price of $2.79 per pound in Washingtion last week, people ought to get their money's worth.

Not that all the exotics are expensive. Spaghetti squash was selling for 29 cents a pound this past wihnter. And one of the most popular items is the very inexpensive tofu, or soybean curd cake.

And not all of Frieda's finest produce is "new". The company also markets parsnips, which went out of style about the time alternatives to winter roots vegetables -- including turnips -- became readily available. Forty years ago they were common; today people don't know how to cook them. So Karen Caplan is developing recipes.

Frienda's Finest has also begun distributing chop suey vegetables -- a one-pound package of cut-up celery, bok choy, onions and bean sprouts -- because of "the Oriental craze," Karen Capalan says.

"and for health food aficionados there are "Munchies," a mixture of sprouted mung and azuki beans and lentils. A delicious, crunchy, low-calorie snack, neither it nor the chop suey vegetables have made their way to Washington yet.

It's only a matter of time.

Karen Caplan, who developed the recipes below, has advice on how to get the maximum life out of some of the new foods.

Spagetti squash and sweet dumpling squash will keep a couple of months in a cool dry place if the stem is intact.

Jicama will keep for 2 to 3 weeks in a cool, dry place .

Enoki mushrooms are very perishable. They should be used in a day or two.

Danish garden cress has a month's shelf life after harvesting, if refrigerated.

Sunchokes, the roots of a species of sunflower, may be kept in the refrigerator for 2 or 3 months. Keep them away from fluorescent lights or they will turn green.

Sprouts of any bean will keep 7 to 10 days in the refrigerator. If they become limp, swish them with water and drain.

Hothouse cucumbers should not be kept in the refrigerator, but in a cool, dry place. They will keep a week.

Shallots, like onions, should be kept in a cool, dry place.

CRUNCHY MUNCHIE SALAD

[6 servings]

3/4 cup sprout munchies or mixture of sprouted beans 1/2 hot house cucumber, thinly sliced 3 1/2 ounces enoki mushrooms, woody bottoms cut off 1/4 cup Danish garden cress or alfalfa sprouts 1 pound peeled, thinly sliced sunchokes 2 1/2 tablespoons sliced pimientoes 3 tablespoons sliced black olives 2 tablespoons vegetable oil 1 tablespoon red wine vinegar 1/4 teaspoon minced garlic

Freshly ground black peper

Separate mushrooms. Toss all vegetables in large mixing bowl. Combine oil, vinegar, garlic and pepper and spoon over vegetables. Allow to sit at room temperature for 30 minutes. Then chill and serve on lettuce leaves.

SUNCHOKES AU GRATIN

[4 to 6 servings]

1 pound peeled, sliced [1/8 inch thick] sunchokes 1 3/4 cups freshly grated parmesan cheese 3/4 cup milk 1/4 cup bread crumbs

In lightly oiled baking dish, layer 1/3 of sunchokes then 1/2 cup cheese. Repeat twice, ending with 3/4 cup cheese. Poor in milk and sprinkle with bread crumbs. Cover with foil and bake at 350 degrees for 35 to 40 minutes, until sunchokes are tender. If mixture seems to be drying out, add a little more warm milk.

JICAMA NIBBLE

1 jicama, peeled and very thinly sliced Juice of 1/2 lime Crushed red pepper or powdered chiles

Arrange jicama on serving platter. Squeeze lime juice over slices. Garnish with lime slices and crushed pepper.

SPAGHETTI SQUASH-ZUCCHINI CASSEROLE [4 to 6 servings]

1/2 Large cooked spaghetti squash 1 cup grated zucchini 1 cup freshly grated cheddar cheese 1 cup tomato sauce Dash garlic powder 1/4 teaspoon dried basil 1/2 teaspoon black pepper 2 tablespoons freshly grated parmesan cheese

To cook squash: Cut in half lengthwise and clean out seeds. Place squash cut side down in a pot with 2 inches of water. Cover and boil for 20 minute. Scoop out "spaghetti" from inside of the squash; reserve shell. Mix spaghetti squash with other ingredients except for parimesan cheese. Spoon mixture back into squash shell and sprinkle with parmesan. Bake at 350 degrees for 30 minutes. CAPTION: Picture 1, Karen Caplan holds a spaghetti squash, one of the funny food available at Washingtion markets; by John Barr for The Washington Post.; Pictures 2 and 3, Enoki doke, left, is one of the more exotic foods featured at Frieda's; photos by John Barr for The Washington Post.