Prepare the lentils: start by rinsing the lentils with cold water in a mesh strainer. Then combine the lentils with the water in a saucepan. Cover and bring to a boil. Once boiling, turn the heat down to medium-low and let it simmer for 20-25 minutes. Then drain the lentils and set aside.
While the lentils are cooking, prepare the base for the sloppy joes. Start by heating a large skillet (I prefer cast iron) over medium heat. Add the olive oil, onion, bell pepper, and garlic. Use a wooden spoon to stir frequently for about 4-5 minutes, until the vegetables start to soften and turn slightly brown. Season with a pinch of salt and pepper.
Next, add the chili powder, paprika, tomato sauce, ketchup, mustard, and maple syrup. Stir to combine, turn the heat down to medium- low, and let it simmer for 2-3 minutes.
Add the cooked lentils and stir to combine. Let the mixture simmer for 5-10 minutes to develop the flavor.
Serve the mixture on toasted buns with your favorite accompaniments.