Quick and easy. Brown ground round and add a taco seasoning mix with 3/4 cup water. Let it cook down. Dice tomatoes, onions, and lettuce. Open a can of sliced black olives, some sour cream light, and a bag of shredded cheese. Scoop out some avocados and slice them.(on sale for 2 for a buck right now). On your tostada shell put the meat, sour cream, tomatoes, olives, onions, cheese, and avocado.
Make Mexican rice to go with it. Fry some extra long grain rice with diced onions in a little olive oil. Add 4 tablespoons of Goya brand Sofrito sauce mix. Add 2 cans of chicken broth. Put the lid on and cook on low to medium low flame until the liquid is almost all the way absorbed. This is what you end up with: