Preheat your oven to 375°F (190°C) and prepare a small baking dish.
Slice the tops off the bell peppers, remove the seeds and white ribs from the inside, and set them aside.
In a large skillet over medium-high heat, add the olive oil along with the diced onion and minced garlic.
Sauté for 3-4 minutes until the onions are translucent and the garlic is fragrant.
Add the ground beef to the skillet, breaking it up with a wooden spoon, and cook until fully browned.
Stir in the chili powder, cumin, sea salt, black pepper, and tomato puree.
Reduce heat to low and simmer the beef mixture for 5-7 minutes until the sauce has thickened slightly.
Divide the beef chili mixture evenly between the two hollowed bell peppers, packing it down gently.
Place the stuffed peppers upright in the baking dish and add 2 tablespoons of water to the bottom of the dish.
Cover the dish tightly with foil and bake for 25-30 minutes until the peppers are soft and tender.
Remove from the oven and garnish with freshly chopped cilantro before serving hot.