Step 1

In a large microwave-safe bowl, stir the beans, cumin, coriander and ¼ teaspoon each salt and pepper. Cover and microwave on high until hot, 3 to 3½ minutes, stirring once. Stir in the vinegar, then mash until smooth. Cool completely. Stir in half the cheese, the pickled jalapeños and cilantro; taste and season with salt and pepper. Divide the filling among the tortillas, spreading it over half the surface. Fold the unfilled side over the filling; press to seal.

Step 2

Set a 12-inch nonstick or cast-iron skillet over medium. Evenly sprinkle half of the remaining cheese into pan; when it begins to melt, place 2 quesadillas directly on top, folded sides facing in. Cook until the cheese on the bottom has formed a golden brown crust, about 5 minutes. Using a spatula, flip each quesadilla; cook until the second sides are spottily browned, 1 to 2 minutes. Transfer to a cutting board. Cook the remaining cheese and quesadillas in the same way. Cut each in half and serve with cilantro, sour cream and hot sauce.