In a large skillet, saute onion in 1 tablespoon oil until tender. Place in a large bowl. Add chicken, crumbs, Parmesan, eggs, herbs and seasonings; mix well. Stir in enough milk to be able to shape mixture into patties. Shape into eight patties. In the same skillet, cook patties in remaining oil for 5 minutes or until browned on each side and heated through. Serve on rolls with lettuce and tomatoes.