1.Preheat oven to 425°F, and line a baking sheet with foil and set aside.
2.Stir together masa and baking powder; then stir in chicken broth, adding a little more broth if dough is too dry. (It should be very moist, but not sticky.)
3.Quickly shape dough into four circles that are 3-inches wide with a ½-inch rim. Place on baking sheet.
4.Spray the dough heavily with nonstick cooking spray. Bake for 30 minutes. Remove pan from oven and spray two or three times more during cooking to make them crisp.
5.While sopes are cooking, spray a small skillet with nonstick cooking spray and place over medium-high heat. Add onion and cook for a few minutes, stirring frequently.
6.Stir in peppers, tomato, and chorizo and cook for 5 more minutes.
7.Spoon a heaping tablespoon of beans onto each sope then top with equal amounts of vegetable mixture. Sprinkle each with a tablespoon of cheese and bake for 5 more minutes.