Heat oil in large skillet and saute onion rings. Cut sausage into 1" diagonal slices; add to onions, cooking until done.
While sausage cooks, rinse and dry fresh salad greens; stir in dressing and arrange on platter. Turn off heat under sausage; pour off fat. Add corn, warm for 1 minute. Using a slotted spoon, place sausage and corn on top of salad greens; top with drained salsa.
Serve with Italian bread, breadsticks, rolls or tortilla chips.