Make tostada bowls: Preheat oven to 300°F. Brush tortillas on both sides with vegetable oil. Place them in oven safe bowls to create bowl-like shapes. Bake for about 15-20 minutes, checking occasionally to prevent burning. Remove from oven and keep in the bowl until cool.
In a large bowl, combine chopped lettuce, black beans, tomato, corn, and some lime juice.
Place the salad in the tostada bowl, top with steak, sour cream, jalapeños, cilantro and hot sauce.