Ingredients:

  Amount  Measure       Ingredient -- Preparation Method
--------  ------------  --------------------------------
     1/3  cup           margarine
   3      tablespoons   corn starch
     1/2  teaspoon      salt
     1/8  teaspoon      pepper
   3      cups          milk
   1                    onion -- chopped
   2      cans          tuna -- drained and flaked
                        -- (7 oz. each)
   1      package       elbow macaroni -- cooked and drained
                        -- (8 oz.)
   1      package       frozen peas -- thawed (10 oz.)
   1      cup           shredded cheddar cheese

Preparation:

In saucepan melt margarine over medium heat. Stir in corn starch, salt and pepper until smooth. Remove from heat; gradually stir in milk until smooth. Bring to boil over medium heat, stirring constantly, and boil 1 minute; add onion. Place remaining ingredients in greased 2 quart casserole. Stir in corn starch mixture. Bake in 350F oven 25 minutes or until heated.