Preheat your oven to 375°F (190°C).
Slice the tops off the bell peppers, remove the seeds and membranes, and set the peppers upright in a baking dish.
In a large skillet over medium heat, add the avocado oil and sauté the diced yellow onion and minced garlic until translucent and fragrant.
Add the ground beef to the skillet, breaking it apart with a wooden spoon, and cook until fully browned.
Stir in the cooked brown rice, tomato sauce, smoked paprika, sea salt, and black pepper, allowing the flavors to meld for 2 minutes.
Spoon the beef and rice mixture evenly into the hollowed bell peppers.
Pour a splash of water into the bottom of the baking dish, cover with foil, and bake for 25 minutes.
Remove the foil and bake for an additional 5-10 minutes until the peppers are tender and slightly charred.
Garnish with freshly chopped parsley before serving.