01 - Preheat the oven to 375°F.
02 - Place the hollowed bell peppers upright in a baking dish. Set aside.
03 - Heat olive oil in a large skillet over medium heat. Add chopped onion; sauté 3 minutes until soft. Add garlic and cook 1 minute more.
04 - Add ground beef and cook, breaking it up, until browned and cooked through—about 6 minutes. Drain excess fat if needed.
05 - Stir in cooked rice, oregano, basil, cumin, cinnamon, parsley, mint (if using), half the chopped tomatoes, and tomato paste. Season with salt and pepper. Cook 3-4 minutes, stirring to combine and heat through.
06 - Carefully spoon the beef and rice mixture evenly into each bell pepper.
07 - Mix the remaining chopped tomatoes with the broth and pour around the peppers in the baking dish.
08 - Cover the dish with aluminum foil and bake for 30 minutes.
09 - Remove foil, top with crumbled feta (if using), and bake uncovered for an additional 10-15 minutes, until peppers are tender and cheese is golden.
10 - Garnish with extra parsley. Serve hot, spooning some sauce over each pepper.