Pulse chicken in a food processor 6 times or until ground. Add onion and next 7 ingredients; process 2 minutes. Shape into 8 patties.
Cook patties in a lightly greased nonstick skillet 5 minutes on each side or until done.
Spread cut sides of rolls evenly with mustard. Place onion and tomato on bottom halves; top each with 2 sausage patties and lettuce. Cover with top halves.
Note: To grill sausage, heat a grill rack coated with cooking spray over medium-high heat (300° to 350°). Grill patties, covered with grill lid, 5 minutes on each side or until done.