Start by preheating your oven to 180°C (350°F) and lightly greasing a baking dish to hold the peppers upright.
Using a sharp knife, carefully cut off the tops of each bell pepper and scoop out the seeds and membranes, creating a hollow cavity for the filling.
Place the peppers in a steamer basket or microwave-safe dish and steam for about 5 minutes until they soften slightly but still hold their shape. This helps prevent overcooking during baking.
Meanwhile, cook the quinoa in boiling water according to package instructions, until it’s fluffy and the water is absorbed. Let it cool slightly.
In a mixing bowl, combine the cooked quinoa, diced tomatoes, black beans, chopped herbs, minced garlic, and a drizzle of olive oil. Season generously with salt and pepper, then stir until everything is well mixed and aromatic.
Using a spoon, stuff each pepper generously with the filling, pressing down slightly to pack it in without overflowing.
Arrange the stuffed peppers upright in your prepared baking dish, then drizzle a little olive oil over the tops for extra flavor and caramelization.
Bake the peppers in the preheated oven for about 25 to 30 minutes, until the tops are bubbly, edges are slightly charred, and the peppers are tender.
Remove the dish from the oven and let the peppers rest for 5 minutes, allowing the filling to set and flavors to meld.
Garnish with extra fresh herbs or a squeeze of lemon, then serve hot for a comforting, colorful meal.