Cook the bacon in a heated cast-iron pan until the fat starts to render. Add the onion and green bell peppers. Cook until the vegetables are soft, about 5 minutes. Add the pork and beans, ketchup, molasses, vinegar, hot sauce, dry mustard and pepper. Stir to combine. Bring the beans to a simmer. Simmer over low heat for 30 to 40 minutes until thick. Add salt to taste.
Serve hot, topped with chopped red onions.