In a bowl combine chow mein vegetables with tuna, water chestnuts, soup, milk, and soy sauce.
Turn into lightly greased 2 1/2-quart casserole.
Cover top of casserole with crisp chow mein noodles.
Bake, uncovered, in moderate oven (350°) for about 20 minutes, or until heated through.
Makes 6 to 8 servings.