Stacked Enchiladas with Corn and Black Beans

Name: Stacked Enchiladas with Corn and Black Beans
Ingredients: 2 garlic cloves , sliced; 1/2 yellow onion , coarsely chopped; 1 ( 28 - ounce ) can whole, peeled tomatoes; 2 tablespoons all-purpose flour; 2 teaspoons ancho chile powder , or to taste; 1/2 teaspoon dried oregano; 1/2 teaspoon kosher salt; 1/2 cup water; 1 tablespoon olive oil; 12 corn tortillas (6 to 7-inch size); 2 tablespoons olive oil; 2 tablespoons finely chopped red or yellow onion; 1 cup frozen corn; 1/4 teaspoon kosher salt; Pinch black pepper; 1 can black beans , rinsed and drained; 4 ounces queso fresco , crumbled (or feta or Monterey jack); 1 ripe avocado , cut into slices; 4 to 6 radishes , thinly sliced; Leaves from 1/4 bunch cilantro