Set oven to 350 degrees.
Prepare the rice with the first 6 ingredients.
Cut up the sausage into bite sized pieces. Add to a skillet with 1/4 cup water, and bring to a boil. Turn down the heat, cover, and simmer for 5 minutes. Remove the cover, then brown the sausage. Drain on paper towels.
Slice the mushrooms and zucchini. Add the mushrooms, zucchini, and chopped onion to the skillet with the sausage drippings; cook until tender.
Stir vegetable mix, peas, sausage, cheese and milk into the rice in a large bowl. Place into a greased 9x13 pan, cover with foil, and cook for 30 minutes. Let stand for about 5-8 minutes before serving.
Serves approximately 4-6 people.