Preheat your oven to 190°C (375°F). Carefully slice off the tops of the peppers and remove seeds and membranes, keeping the tops to use as lids later.
In a saucepan, combine the rice and lentils with 3 cups of water. Bring to a boil, then reduce heat, cover, and simmer for about 20 minutes until tender and water is absorbed. Fluff with a fork and set aside.
While the grains cook, heat olive oil in a skillet over medium heat. Add chopped onion and minced garlic, sautéing until fragrant and translucent, about 5-7 minutes. The kitchen should fill with a warm aroma as they soften.
Add the cooked grains, diced tomatoes, cumin, paprika, salt, and pepper to the skillet. Stir everything together and cook for another 5 minutes, allowing the flavors to meld and the mixture to slightly thicken.
Fill each hollowed-out pepper with the savory mixture, pressing down gently to pack in the filling. Place the peppers upright in a baking dish and top each with their reserved tops for a charming presentation.
If desired, sprinkle a little more diced tomato or vegan cheese on top of each pepper. Cover the dish loosely with foil to keep everything moist.
Bake the peppers for 30 minutes, until the skin blisters slightly and peppers are tender when pierced with a knife. Check at 25 minutes to avoid over-browning.
Remove from the oven and let rest for 5 minutes. Meanwhile, chop fresh parsley for garnish and squeeze a little lemon juice over the peppers for brightness.
Serve the peppers warm, garnished with parsley and a squeeze of lemon, alongside your favorite salad or crusty bread for a cozy, nourishing meal.