Cut the top of each pepper off, approximately 1 inch of the way down. Remove the ribs and seeds. Next drizzle each with half a teaspoon of oil and rub it all over the peppers. Place in a shallow pan, cut-side down, and bake for 20 minutes. Take the tops out of the oven, but flip the bottoms of the peppers over and bake for 10 more minutes.
While the peppers are cooking, bring the lentils and 1 cup water to a boil in a small pot. Then reduce flame to low, cover, and let cook for 10 minutes. Remove the lentils to a bowl immediately.
Heat 1 tablespoon of the oil in the same pot and sauté the onion and garlic on low flame for about 7 minutes, until translucent. Add in the spinach and cook for about 3 more minutes, stirring occasionally.
Mix together the lentils, sautéed vegetables, tomato sauce, and spices. Divide the mixture between each pepper, then gently place the top of the pepper on each one. Raise the temperature to 450ºF and top each stuffed pepper with cheddar cheese. Cook for 5 minutes.
Notes
TO MAKE VEGAN: Omit the cheese.
Recipe by Lenses and Lentils at https://lensesandlentils.com/tomato-basil-lentil-stuffed-peppers/