Japanese food is easily adapted to vegetarianism and to the meal of the summer season -- a picnic. The following is an approximation of the Nori-Maki Sushi I was served at a Fourth of July picnic for people from a particular region of Japan.

NORI-MAKI SUSHI

(Makes 4 rolls, enough for 6 servings)

1 cup short-grained brown rice

2 cups water

4 sheets dried nori seaweed

1/2 teaspoon salt

2 to 4 tablespoons rice vinegar

2 teaspoons honey

FOR THE FILLINGS (choose 3 for each roll):

1 tablespoon grated raw carrot

1 tablespoon cooked chopped spinach

1 teaspoon toasted sesame seeds

1 tablespoon each of scallion strips, bell pepper strips, celery strips, lightly steamed asparagus strips or green beans, and omelet strips

2 or 3 avocado chunks

2 teaspoons chopped watercress

1/2 teaspoon pickled umeboshi plum (plum flavored paste available at oriental stores)

1 tablespoon mushrooms, chopped (see note below)

FOR THE CONDIMENTS:

1/2 cup pickled ginger

1/2 cup sweet and hot mustard

1/2 cup shoyu

Cook rice, uncovered, in boiling water for 5 minutes. Cover and reduce heat to low, simmer for 45 minutes.

While the rice is cooking, select and prepare your choice of fillings. You will be making 4 rolls. Combine 3 of the suggested ingredients in each.

Unless the nori sheets you have are pretoasted, wave each one over a flame (a gas burner is ideal), holding with tongs or fingertips so that each sheet changes color and texture slightly, becoming lighter and coarser.

Dissolve salt in rice vinegar in a small saucepan and add honey. Heat gently to liquify. When the rice is cooked, turn it out to a large platter or baking dish with sides. Pour the vinegar mixture over it, stirring as you do and fanning the steam away. A folded newspaper works nicely. When the rice has cooled to room temperature, it is ready.

For rolling the sushi a traditional bamboo mat is great but not essential. A big cloth napkin, just a little larger than the nori sheets, works fine. Place the mat or cloth flat in front of you. Put the first sheet of nori on it. Moisten your fingers with water or vinegar and spread 1/4 of the seasoned rice on the nori, covering it except for an 1 to 2 inches at the top, which you will use to seal the roll.

Across the middle, parallel to the top, form an indentation and place the filling there, forming a thin line from one end to the other. For example, a strip of omelet, a line of chopped watercress and strips of red bell pepper.

Grasping the nearest side of the mat, roll it up and away from you toward the top, pressing the whole thing together tightly. Dampen the remaining flap of nori and seal the roll by pressing the flap along the length of the roll. Place the roll on a cutting board and slice it with a very sharp knife into 1-inch segments. Arrange cut side up and serve.

Note: Ordinary mushrooms can be used, chopped and saute'ed, but shiitakes are traditional. Soak several of them in water, then simmer in 2 teaspoons each of sherry and shoyu. Chop fine or cut into strips.