Preheat your oven to 190°C (375°F). Lightly grease your baking dish to prevent sticking.
Cut the tops off the bell peppers and carefully remove the seeds and membranes. Place them upright in the baking dish.
Heat olive oil in a large skillet over medium heat. Sauté the chopped onion and minced garlic until fragrant and translucent, about 2-3 minutes—your kitchen will fill with a warm aroma.
Add the cooked quinoa, rinsed black beans, tomato paste, smoked paprika, and a pinch of salt and pepper to the skillet. Stir everything together and cook for another 5 minutes until heated through and fragrant.
Taste the filling and adjust seasoning if needed—aim for a smoky, spicy flavor with a good balance of salt and heat.
Use a spoon to generously stuff each pepper with the filling, pressing gently to pack it in firmly.
Place the stuffed peppers upright in the prepared baking dish. Cover loosely with foil to trap moisture and help them cook evenly.
Bake in the oven for about 30 minutes, or until the peppers are tender and slightly blistered around the edges, filling bubbling inside.
Remove the foil and bake for an additional 5 minutes to give the tops a slight char and crispy edge.
Take the peppers out of the oven and let them rest for 5 minutes. The filling will set slightly, making them easier to serve.
Garnish with fresh herbs if desired, then serve hot and enjoy the smoky, spicy flavors paired with your favorite side.