sausage, zucchini and rice casserole

1 lb sausage, spicy Italian is really good
1 1/2 cup instant rice
1 1/2 lb zucchini, sliced
1 cup onion, chopped
16 ounce canned tomatoes
1 cup hot water
1 tsp mustard
1 tsp garlic salt
dash of pepper
1/2 cup chopped green chilies, drained
2 cups grated cheese (optional)

Brown sausage and drain. Add rice, zucchini, and onion. Stir and saute. Add tomatoes, green chilies, hot water, mustard, garlic salt, and pepper. Bring to a boil, lower heat and simmer 5 minutes. Sprinkle grated cheese on top. Cover and let cheese melt. Serve immediately.