Preheat your oven to 375°F and lightly grease a small baking dish with a touch of olive oil.
Slice the bell peppers in half lengthwise, removing the seeds and internal membranes to create a hollow boat.
In a skillet over medium heat, add the olive oil and sauté the diced yellow onion until it becomes translucent and soft.
Add the ground beef to the skillet, breaking it apart with a wooden spoon, and cook until it is fully browned.
Stir in the minced garlic, chili powder, cumin, sea salt, and black pepper, and cook for 1 minute until the spices are aromatic.
Add the black beans and tomato puree to the beef mixture, stirring well to combine, and simmer for 3 minutes until the sauce thickens slightly.
Generously spoon the beef and bean mixture into each bell pepper half, pressing down gently to pack the filling.
Arrange the stuffed peppers in the baking dish, pour two tablespoons of water into the bottom of the dish, and cover tightly with foil.
Bake for 25 minutes, then remove the foil and bake for an additional 5 minutes until the peppers are tender and the tops are slightly golden.
Remove from the oven and garnish with fresh chopped cilantro and a bright squeeze of lime juice before serving.