Preheat your oven to 350°F. In an oven-safe skillet over medium heat, add the olive oil, diced onion, green bell pepper, and minced garlic. Sauté for about 5 minutes until the vegetables have softened.
Stir in the apple cider vinegar, ketchup, mustard, brown sugar, barbecue sauce, salt, and pepper. Mix well and add the baked beans with juices. Bring the mixture to a gentle simmer. Place the skillet in the oven and bake for 40-60 minutes until the dish is bubbly.
Remove the skillet from the oven and let the beans cool slightly before serving. Garnish with fresh herbs if desired.