Prep Time: 20 minutes
In a large sauté pan, heat the oil over high flame until hot. Add the onions and peppers, season with a pinch of salt and pepper and reduce the flame to medium. Continue cooking until soft, stirring occasionally, about 15 minutes.
While the onions and peppers are cooking, sear the hot dogs in a non-stick pan on 4 sides over medium flame, about 8 minutes total. Alternatively, grill or poach the hot dogs until heated through.If desired, spread the mustard on the inside of the buns. Place a hot dog in each bun and top with the onions and peppers.