Preheat your oven to 375°F. Slice the tops off the bell peppers, remove the seeds and internal ribs, and set aside.
Place the peppers upright in a baking dish with 0.25 cup of water at the bottom, cover tightly with foil, and pre-bake for 15 minutes.
While peppers bake, heat olive oil in a large skillet over medium heat and sauté the diced yellow onion and minced garlic until translucent.
Add the ground beef to the skillet, breaking it up with a wooden spoon, and cook until fully browned.
Stir in the tomato paste, sea salt, black pepper, and smoked paprika, allowing the flavors to meld for 2 minutes.
Remove the skillet from the heat and fold in the cooked brown rice and non-fat Greek yogurt until the filling is creamy and uniform.
Carefully remove the peppers from the oven and drain any excess water from the dish.
Divide the beef and rice mixture evenly among the peppers, packing it down gently.
Return the stuffed peppers to the oven, uncovered, and bake for another 15-20 minutes until the peppers are tender and the tops are slightly golden.
Garnish with chopped fresh parsley before serving warm.