Grill peppers and chiles until charred on all sides. Remove from the grill, place in a bowl, cover, and let steam for 5 minutes. Remove skin and finely dice.
Melt butter in a 9-inch cast iron skillet on the grates of the grill. Add the potatoes, onions, peppers, and chiles all in 1 layer and pack down. Cook until crisp and nicely browned.
Melt butter in a 9-inch cast iron skillet on the grates of the grill. Add the potatoes, onions, peppers, and chiles all in 1 layer and pack down. Cook until crisp and nicely browned.