Heat the oven to 375°F. Brush all 12 wells of a standard muffin pan with the measured oil. Press one wonton wrapper into each well, then add a second rotated 45 degrees so the corners alternate.
Bake empty cups for 5 to 6 minutes until the bottoms begin to set and the corners are still pale. Leave them in the pan while preparing the filling.
Meanwhile, brown beef and onion in a skillet for 8 minutes until beef reaches 160°F, breaking it into fine crumbles. Drain excess fat and stir in cumin, ancho chile, garlic powder and salt for 30 seconds.
Fold in black beans and salsa and simmer for 2 to 3 minutes until the mixture holds together without loose liquid. Divide filling evenly among the 12 partly baked cups and scatter cheddar over each.
Bake for 10 to 12 minutes until wrappers are golden and centers reach 165°F. Rest in the pan for 5 minutes, then loosen carefully with a small spatula and serve 3 cups per person.