In a skillet, saute onion in butter. Add vegetables. Cover and cook for 5 minutes or until tender; drain and set aside. In a bowl, combine the egg, mustard, Worcestershire sauce, salt and pepper. Crumble beef over mixture and mix well. On a large piece of heavy-duty foil, pat beef mixture into a 16x10-in. rectangle. Cover with vegetable mixture to within 1 in. of edges. Sprinkle with cheese. Roll up, jelly-roll style, starting with a short side and peeling away foil while rolling. Seal seam and ends. Place seam side down in a greased 13x9-in. baking dish. Top loaf with bacon strips. Bake, uncovered, at 350° for 1 hour or until meat is no longer pink and a thermometer reads 160°; drain.
You can easily use whatever vegetable or combination of vegetables your family enjoys in Vegetable Pinwheel Roll.