Preheat your oven to 190°C (375°F) and line a baking sheet with parchment paper.
Wash each bell pepper, then slice off the tops and carefully remove the seeds and membranes, keeping the stems intact if you like a rustic look.
Place the peppers cut-side down on the baking sheet and roast in the oven for about 10 minutes until slightly blistered and beginning to soften.
While the peppers roast, combine cooked grains, beans, chopped vegetables, herbs, cumin, smoked paprika, salt, pepper, and a tablespoon of olive oil in a mixing bowl. Mix everything well until evenly coated and the flavors meld together.
Remove the peppers from the oven and let them cool slightly so they are safe to handle. Then, gently stuff each pepper with the prepared filling, pressing down lightly to pack it in.
Arrange the stuffed peppers upright on the baking sheet and bake for an additional 20-25 minutes, until the peppers are tender and blistered in spots, and the filling is hot and slightly caramelized on the edges.
Once baked, remove the peppers from the oven and let them rest for about 5 minutes. Drizzle with a little more olive oil or a squeeze of lemon for added brightness.
Serve the peppers warm, enjoying the smoky aroma, tender texture, and rustic charm in each bite.