Clean and wash all vegetables, break up lettuce into large bite size pieces and drain well. On a large serving platter, arrange green lettuce in center, place tomatoes, cucumbers, zucchini, and carrots to the surrounding edges. Reserve chilled to side.
In a large skillet over medium-high heat, brown and crumble Italian sausage. Cook until no longer visibly pink and drain.
Arrange hot cooked sausage over chilled lettuce and garnish with red sliced onions, olives and croutons if desired. Sprinkle with olive oil, vinegar, pepper and with grated cheese. Serve guests immediately. Refrigerate leftovers.