Fish or Tofu Enchiladas

Ingredients

• 1 1-1/2-ounce package cooking sauce mix or taco seasoning mix
• 1 8-ounce can tomato sauce
• 1/2 cup water
• 1 tbsp. butter or margarine
• 1 small onion, thinly sliced
• 2 cups white fleshed fish or firm tofu, shredded, cooked
• 1/2 cup sour cream or plain yogurt
• 2 tbsp. Parmesan cheese, grated
• 1/2 tsp. coriander
• 10 corn tortillas
• 1 cup (1/4 pound) Monterey Jack or Cheddar cheese, grated