Heat the oil in a frying pan on medium/high heat, add the onions, and sauté for about five minutes until they start to get shiny. Add the mushrooms and zucchini and gently stir.

Let it cook for about 15 minutes or until the zucchini is cooked through. You don’t want it to cook too long or it will get mushy.

To serve, reheat covered until heated through.