Heat oil in a large heavy skillet over medium-high heat. Cook sausage until browned on both sides; remove and set aside. Drain excess oil. Saute shallot and garlic until tender. Stir in tomatoes, corn, peas, mushrooms and green onions. Season with bay leaf, thyme and red pepper flakes. Bring to a boil, then carefully transfer to a 9×13 inch baking dish. Lay sausage on top, and cover dish tightly with foil.