Cut onion into 1/2 inch squares
Thinly slice the mushrooms
Thinly slice the Yellow Squash and Zucchini. You should have 3-4 cups of squash.
Cut tomato into 1/4 inch pieces
Heat olive oil in a large skillet or wok until hot. This could take 3-4 minutes.
Sauté onion until transparent.
Add mushrooms and cook for 5 minutes
Add squash and cook for a few minutes. They should still be firm to the touch.
Season with salt & pepper
Stir in tomatoes and serve