FOR 50 YEARS spinach has been allied with the wrong hero. It should have been Cinderella. Once the stepchild of the vegetable family, it was the butt of culinary scorn, at least in this country where children were expected to always use "ugh" as a prefix for "spinach." Popeye's dependence on spinach to give him superhuman strength merely illustrated Popeye's bravery in eating the stuff, so the short surge of popularity for canned spinach around 1929 -- when Popeye was born -- probably had more to do with courage than acceptability.

Now, however, half a century after cartoonist E. C. Sezar tried to immortalize spinach through Popeye, movie director Robert Altman is trying again to immortalize Popeye. Spinach, in the meantime, has become the belle of the ball, being sought for dips and quiches, souffles and stuffings, the most fashionable of salads and the softest bed for poached eggs or fish. From France, spinach pureed with pears is a fashionable escort for a main dish. And from Italy, the greening of pasta is leaving a trail coast to coast.

It is hard to remember how anyone could have hated spinach.

It has one advantage in being readily available year round. The naturalist can buy it loose and strip each young leaf from its clump of stems. The harried can substitute frozen spinach, one of the most satisfactory of frozen vegetables. And the supermarket shopper can nearly always find fresh spinach already packed in cellophane bags.

The only tricks to handling spinach are to pull off the tough stems, to wash it carefully -- swishing it around in a basin of water and lifting it from the water so the sand stays behind -- and to cook it very briefly in only the water that clings to the leaves, stirring once or twice to expose all the leaves to the heat. Frozen spinach can be defrosted and drained thoroughly, then used as-is in spinach recipes or heated through briefly with butter or oil. To avoid interaction between the vegetable's minerals and metal utensils, cook spinach in stainless steel or enamel rather than iron or aluminum pans, and never serve in a silver dish, even if it has joined respectable company.

Fresh spinach shrinks considerably when cooked, so a 10-ounce bag can be expected to reduce to one cup and serve two people. Loose spinach has more waste, and a pound equals approximately a 10-ounce bag after trimming.

Only small boys who read comics turn super-strong immediately after eating spinach, but it is a nutritious vegetable, particularly when you consider how low in calories it is. It contains substantial rations of vitamins A and C, plus B complex, fiber and -- of course -- iron.

Originally from Persia, spinach has been served from soup to nuts -- or chocolates, in the case of the original Italian florentine candies. It mates well with cream and cheese -- especially Swiss, parmesan and ricotta. It has a natural affinity for nutmeg, and is enhanced by lemon and vinegar.

And it still, like Popeye, goes with Olive Oyl.

This soup is light and low in fat, with an unusual but subtle flavor. It is also extremely easy to make. Part of its appeal is in the spinach retaining some bite, so cooking time should be followed carefully. Wild mint can still be found growing this time of year, and is definitely worth the search for this soup. AMERICAN INDIAN FISH AND SPINACH SOUP (8 to 10 servings) 1 large potato, diced 1 large onion, diced 6 peppercorns 10 dried juniper berries 2 quarts water 1 1/2 pounds flounder filets, or other delicate white fish 1 pound fresh spinach (or 10-ounce bag) 10 fresh mint leaves or 1/4 teaspoon dried mint 1 1/2 teaspoons salt

Simmer potato, onion, peppercorns and juniper berries in water for 3/4 hour uncovered. Mash juniper berries with a spoon against the side of the pot. Add fish and simmer 5 minutes, breaking fish into small pieces. Wash and trim spinach of tough stems. Stir spinach into the broth, along with mint and salt. Simmer just 5 minutes more. Serve hot. LAMB WITH SPINACH AND EGG LEMON SAUCE (4 servings) 6 tablespoons butter 2 onions, chopped 1 1/2 pounds lamb cut in 1-inch cubes (ground lamb can be substituted) 1 teaspoon salt Pepper to taste 3/4 cup beef broth 1 1/2 pounds spinach, washed, trimmed 2 egg yolks 2 tablespoons lemon juice

Heat 4 tablespoons butter and saute onions in it until they are golden. Add lamb cubes and brown 5 minutes over high heat. Add salt, pepper and beef broth. Cover and simmer until lamb is tender, about 45 minutes. In another pan, cook spinach 5 minutes. Drain and chop coarsely. Spread on top of lamb and dot with remaining 2 tablespoons butter. Simmer 15 minutes and turn off heat. Beat egg yolk until light. Remove 2 tablespoons broth from the pot and stir into yolks, along with the lemon juice. Pour over the lamb and reheat over very low heat. Be sure not to boil, or the sauce will curdle. Serve hot. SPINACH DIP 1 package frozen chopped spinach, defrosted 1 cup mayonnaise 2 tablespoons finely chopped onion 1 teaspoon lemon juice 1/4 teaspoon pepper

Stir ingredients together and refrigerate. Serve with raw vegetables for dipping. SPINACH AND BACON SALAD (4 servings) 1 pound fresh spinach 2 tablespoons vinegar 1/4 cup olive oil Pinch of sugar Salt and pepper 1 avocado, diced 8 slices bacon, preferably nitrate-free 2 hard-cooked eggs, chopped

Wash and trim spinach, pat dry in towel. Stir together in a large bowl vinegar, olive oil, sugar, salt and pepper. Toss in avocado cubes, coating well with the dressing. Fry bacon until crisp. Drain and reserve fat. Break bacon into large pieces. Toss spinach, eggs and bacon with the avocado and dressing. Pour 6 tablespoons hot bacon fat over salad, toss again and serve immediately. ROMAN STYLE SPINACH (4 to 6 servings) 2 pounds fresh spinach, washed and trimmed 2/3 cup olive oil 8 scallions, chopped 8 cloves garlic, sliced Salt and pepper 1 lemon, cut in wedges

Cook spinach in the water that clings to its leaves, just until it wilts. Drain and press out moisture. Heat olive oil and saute scallions and garlic unitl they wilt but do not brown. Toss with spinach. Season with salt and pepper. Let cool to room temperature and serve with lemon wedges. KOREAN SPINACH (2 or 3 servings) 1 pound fresh spinach, washed and trimmed 1 tablespoon soy sauce 2 tablespoons sesame oil (Oriental style sesame oil, which is heavier and darker than American style) 1 tablespoon sesame seeds 1 clove garlic, crushed 1 teaspoon sugar 1 teaspoon vinegar Pepper to taste

Steam spinach in just the moisture that clings to its leaves, just until tender, less than 5 minutes. Drain and squeeze out as much water as possible. Chop coarsely. Combine remaining ingredients and mix with spinach. Serve hot or cold.