Mexican Beef Salad

This salad is a revision of one I got from Weight Watchers.

8 cups lettuce, bite size pieces
4 Roma tomatoes, sliced
8 ounces deli roast beef, shaved and cut into strips
2 avocadoes, sliced
1 can black beans, rinsed and drained well
1 medium onion, diced
1/4 cup lime juice
2 Tbsp olive oil
2 Tbsp water
1/2 tsp minced garlic
1/2 tsp ground cumin
1/2 tsp salt
1/2 tsp hot sauce
fresh cilantro, optional

Divide lettuce among 4 dinner plates.  Top with tomato slices, roast beef and avocado.
Mix together the lime juice, olive oil, water, garlic, cumin, salt, and hot sauce.  Stir in beans and onions.  Divide bean mixture (with all the juice) between the 4 plates, spooning on top of the lettuce. 
Top with the cilantro if desired.

Serve with warm tortilla or tortilla chips.