Preheat your oven to 375°F (190°C) and prepare a small baking dish by adding two tablespoons of water to the bottom.
Slice the tops off the yellow bell peppers and carefully remove the seeds and membranes from the inside.
Finely dice the yellow onion and mince the garlic clove.
Heat a non-stick skillet over medium-high heat and add the ground beef and diced onion, cooking until the beef is browned and the onion is translucent.
Stir in the minced garlic, sea salt, black pepper, dried oregano, and smoked paprika, cooking for another 60 seconds until fragrant.
Add the cooked brown rice and tomato puree to the skillet, stirring well to combine all ingredients into a thick filling.
Spoon the beef and rice mixture into the hollowed-out bell peppers, pressing down gently to pack the filling tightly.
Place the stuffed peppers upright in the prepared baking dish and cover the dish tightly with aluminum foil.
Bake for 30 to 35 minutes, or until the peppers are fork-tender but still hold their shape.
Remove from the oven and let cool for 5 minutes before topping each pepper with a generous dollop of non-fat Greek yogurt.