Ingredients
3 tablespoons olive oil
1 medium onion, finely diced
1 medium bell pepper, finely diced
1 pound ground beef
One 15-ounce can diced fire-roasted tomatoes
One 15-ounce can kidney beans, drained and rinsed
1/4 cup tomato paste
2 tablespoons apple cider vinegar
1 teaspoon brown sugar
Kosher salt and freshly ground black pepper
4 hamburger buns