Preheat your oven to 375°F (190°C) and lightly grease a small baking dish.
Slice the tops off the bell peppers and remove the seeds and membranes from the inside.
In a large skillet over medium heat, add the olive oil and sauté the finely diced onion and minced garlic until fragrant.
Add the ground beef to the skillet, breaking it up with a spoon, and cook until browned and fully cooked through.
Stir in the cooked brown rice, tomato puree, sea salt, black pepper, smoked paprika, and turmeric until well combined.
Spoon the beef and rice mixture into the hollowed-out bell peppers, pressing down gently to pack the filling.
Place the peppers upright in the baking dish, add a splash of water to the bottom of the dish, and cover tightly with foil.
Bake for 30 minutes, then remove the foil and bake for an additional 10 minutes until the peppers are tender and slightly golden.