Place red bell pepper, pasilla (or poblano), and Fresno (or red jalapeno) chile peppers under broiler. Broil under high heat, turning until charred on all sides. Using tongs, carefully transfer peppers to paper bag. Seal the top and allow peppers to steam for 10-15 minutes. Remove charred skin, stems, seeds, and membranes from peppers. Slice peppers thinly.
Preheat oven to 375 degrees. Wash potatoes well, scrubbing skins. Dry potatoes. Rub skins with ½ tablespoon of olive oil. Bake for one hour or until they reach desired doneness.
Meanwhile, heat 1 ½ tablespoons olive oil over medium low heat in skillet. Sauté onion until it is golden brown, about 10 minutes. Add sliced roasted peppers to onions and continue cooking, stirring occasionally around 8 minutes.
When potatoes are baked to desired level, remove from oven and make a slit in the top of each one. Place desired amount of butter and sour cream inside each potato. Season with salt and pepper. Top potatoes with pepper and onion mixture. Serve immediately.