Lean meats. Chicken breast, steak, turkey breast, even lean pork cuts and fish.
There's no magic here. You need protein...eat it. Whether its on the salad, or next to it...eat it.
REmember cheese and egg are protein sources too, and egg whites have zero fat too. When I hit the salad bar across the street ($4.99 a pound), I get lots of meat, veggies and a bit o tastey stuff like bacon bits and eggs. VERY light on the dressing...as the dressing overload is what turns most people's healthy salad into a fatty 'lost cause'.