Rice paper, the phyllo-thin Southeast Asian pastry wrapper, is the key to what has been called Vietnam's national dish, the tasty spring rolls known as cha gio. These little cylinders are rolled with a stuffing of seafood, pork, mushrooms and chives, fried twice to a crispy goldness and served cut in sections with lettuce leaves for wrappers, Asian basil, coriander leaves, sliced cucumber and chili peppers, and a fiery, garlicky sauce.

Cha gio, which make an unusual appetizer or first course, are simple to make and lend themselves to a group effort. Once cooked and set out, dinner guests create their own lettuce packages.

It is next to impossible to make rice paper, which consists of a dough of rice flour, water and salt, by hand; you must buy it already made. It's one of those rare cases where a machine makes a better product than all but the most well-practiced human being.

Rice paper comes in various sized rounds and triangles. The most practical for spring rolls is the 8-inch round sold dried in one-pound packages in stores carrying Vietnamese and other Southeast Asian foods. The yield is 45 to 50 sheets.

The sheets are brittle and must be handled with care. To soften, each should be brushed liberally on both sides with water or, better yet, beer, which yields a deeper golden color when the rice paper is fried. Each sheet should sit for a minute or two until it is soft and workable. Once soft, they may be stacked and covered with a damp towel as you work.

With some imagination and practice all sorts of fillings can be concocted that should work well with these sheets -- fruit fillings for example -- and the pastries can be pan-browned as well as fried. Depending on one's folding ability, the pastry shapes needn't be limited to the standard "roll."

In keeping with tradition however, the best known use for rice paper is as follows: CHA GIO (Vietnamese Spring Rolls)

(8 to 10 servings as an appetizer)

* 2 tablespoons dried tree ear mushrooms

2 ounces cellophane (bean thread) noodles

1 pound ground pork

1/2 pound chopped shrimp

1 tablespoon fish sauce (nuoc mam)

1 teaspoon salt

1 teaspoon freshly ground pepper

2 garlic cloves, minced

1/4 cup chopped red onion

1/4 cup chopped Chinese chives (or scallions)

Rice paper, 8-inch rounds, 1 pound package

1 cup beer, approximately

1 egg, beaten

Oil for frying

Leaves from 3 heads of iceberg lettuce (or other lettuce that won't just wilt when spooned with hot sauce)

1/2 cup basil leaves, preferably Asian basil

1/2 cup mint leaves

1/2 cup coriander leaves

2 cucumbers, peeled, seeded and sliced

6 red chili peppers, sliced thinly into rounds, seeds and all

FOR THE SAUCE:

1/4 cup minced garlic

1/2 cup fish sauce

1/3 cup lime juice

1 tablespoon sugar

1 teaspoon Sa-te oil (or chili oil)

Peanut oil for deep-frying

Cover the tree ear mushrooms with boiling water and allow to stand 15 minutes. Cover the cellophane noodles with boiling water and allow to stand for 15 minutes. With a heavy knife chop the pork to a finer consistency. Put the pork in a mixing bowl with the shrimp, fish sauce, salt, pepper, garlic, onion and chives. Drain the tree ears, rinse and dry them, chop very lightly, and add to the pork and seasonings. Drain the cellophane noodles and chop roughly. Add one cup of them to the pork mixture. Mix these ingredients well with your hand or a spoon, stirring in one direction.

Taking a sheet at a time, brush each side of the rice paper with the beer and set aside. After a sheet softens, which takes a minute or two, it can be stacked and covered with a cloth until ready to use. Stop after you've done about half of the rice paper.

Take one sheet of the rice paper and lay it in front of you. Paint the edge of the top half with a little beaten egg. Put a heaping tablespoon of filling across the bottom third of the rice skin, stopping an inch from either edge. Fold the bottom flap over the filling, and then fold the sheet again with the filling. Fold the sides in over the filling and continue to roll. Press the edges to seal. Heat oil for deep-frying in a large wok or skillet.

Meanwhile put the lettuce leaves on a platter or basket, and arrange the basil, mint, coriander, cucumbers and chili pepper slices on a small platter, and put both on the dining table. Mix all the sauce ingredients and set out in one or two bowls.

When the oil is hot, about 350 degrees, add as many spring rolls as will comfortably cover the surface of the oil. Fry 5 minutes and remove to drain on paper towels. Repeat until all the spring rolls are done. Turn up the heat under the oil and again add the spring rolls, and fry them for another 2 minutes. Remove to a cutting board. Pat lightly with paper towels. When cooled slightly, cut into 3 or 4 sections. Remove to a serving platter and put with the other ingredients. Each diner should take a lettuce leaf, put in a couple of spring roll sections, any or all of the garnishes, sprinkle these to taste with the sauce, roll and eat.

Note: Most Chinese groceries carry tree ear mushrooms, cellophane noodles and fish sauce, but it is necessary to visit a store specializing in Southeast Asian goods to buy rice paper, Asian basil, mint, and Sa-te oil.