Heat vegetable oil in a skillet and sauté onion, red pepper, and garlic until soft, about 2-3 minutes. Add cumin and let mixture cool.
Place beans in a food processor with 1 teaspoon salt and chipotle peppers. Process until beans are mostly in small pieces. Add the onion mixture and do a few more pulses to get everything mixed well. Transfer to a medium bowl.
Add corn, pumpkin, and panko crumbs to the beans mixture and mix together well. If the mixture feels to loose and will not hold its shape well, add extra panko crumbs.
Shape into 8-10 slider-sized patties and place on a large plate or tray. Refrigerate for 30-60 minutes.
To make sauce, mash together the avocado, sour cream, and lime juice until smooth. Or you can process them in a food processor. Add red onion and salt. Refrigerate until needed.
Heat oven to 375 degrees. Spray both sides of sliders with cooking spray and place on a foil-lined baking sheet. Bake for about 6-8 minutes per side. Alternately you can sauté them in 2 tablespoons of vegetable oil for about 3 minutes per side.
Serve on slider buns with avocado sauce, tomato, and cilantro.