Preheat your oven to 190°C (375°F). Slice the tops off each bell pepper and carefully remove the seeds, creating a hollow cavity for the filling.
Heat the olive oil in a saucepan over medium heat. Add the diced onion and sauté until translucent and fragrant, about 5 minutes, releasing a sweet aroma.
Stir in the minced garlic and cook for another minute until fragrant, making sure it doesn’t burn.
Add the cooked quinoa, drained black beans, chopped tomato, smoked paprika, and chopped herbs to the pan. Mix well and cook for 2-3 minutes to combine the flavors.
Use a spoon to gently stuff each pepper with the filling mixture, pressing down lightly to pack it in.
Arrange the stuffed peppers upright in a baking dish. Cover loosely with foil to trap steam and help soften the peppers.
Bake in the preheated oven for 25-30 minutes, until the peppers are tender and slightly blistered on the skin.
If using vegan cheese, sprinkle it over the peppers in the last 5 minutes of baking, then return to the oven until melted and bubbly.
Remove the peppers from the oven and let them rest for 5 minutes, allowing the filling to set slightly and making them easier to serve.
Garnish with extra chopped herbs if desired, then serve warm with a squeeze of lemon or a drizzle of olive oil for extra brightness.