Preheat an outdoor grill, indoor griddle or grill pan to medium-high heat. Parboil the hot dogs for a few minutes to heat through. In a medium saucepan, heat the beans over medium heat (or cover and heat in the microwave on high for 3 minutes), adding a little water to thin slightly.
Meanwhile, grill the poblano (or cook over an open flame on the stovetop or under the broiler) until evenly charred. Transfer to a bowl, cover and let cool, then peel and slice.
Make the ponchos: Top each of 4 tortillas with a thin layer of salsa verde, a swirl of mustard, a few slices of poblano and lots of cheese, then cover each with another tortilla. Spread the top tortilla with some beans and set a dog at one end. Wrap and roll up the tortilla stack around the dog; repeat with the remaining ingredients. Spray the ponchos with cooking spray and grill for a few minutes to brown and crisp the tortillas.