skip the lettuce , it's a waste of space.
broccoli, spinach, cauliflower, red peppers, green peppers, cabbage, zucchini, onion, tomatoes, cucumber, mushrooms, celery ... to name a few vegetables.
Adding egg, fish or chicken pieces gets you your protein.
Throwing in some sunflower seeds or almond slices can't hurt.
If the diet is to lose weight, balsamic vinegar is all you need to dress it.
Stay away from low fat dressings as they usually have sugar and starch.
Regular dressing and oil are high in calories, but it may be argued, could be better for weightloss than low fat dressings.
Make a white dressing out of plain lowfat yogurt, vinegar and spices if you want some extra protein, along with some carbs.