Chicken Tostadas

Name: Chicken Tostadas
Ingredients: 3 tablespoons vegetable oil or bacon drippings; 2 garlic cloves, crushed; 2 cans (15 ounces each) black beans, undrained; 1/3 cup sour cream or plain yogurt; 3 tablespoons Frontera Red Chile or Chipotle Hot Sauce, plus more for serving; 6 cups sliced romaine lettuce leaves; 12 tostadas (crisp-fried corn tortillas), store-bought or homemade; 2 cups coarsely shredded cooked or grilled chicken; 2 ripe tomatoes, thinly sliced; 1 ripe avocado, pitted, flesh scooped from skin and cut into ¼-inch pieces (optional); About ¾ cup grated Mexican queso añejo or Romano cheese; ½ to ¾ cup (loosely packed) chopped cilantro