Just about anything tastes great in a salad and really breaks up the monotony of plain lettuce tomato. Of course, start with lettuce as a base, but left over chopped meats, steamed veggies, water chestnuts, fruits, cheeses, even cooked dried beans and texture, protein, and nutrients.
You can even turn that "garbage salad into a complete meal by topping with quinoa or rice and protein ot chilli w/tomato, onion and a slice or two of avocado. Salsa also makes a great dressing!!!