Soak the lentils in clean water for 15 minutes while you prep the veggies. Drain the lentils and bring to a boil in a medium saucepan filled with water. Simmer for 10 minutes. Drain, and set aside.
In a large bowl combine the chopped onions, peppers, chilies, garlic, corn, and lentils. Stir well to evenly distribute all the vegetables and beans.
Add it all the brown sugar, honey, (or agave) ketchup, mustard, horseradish, tomato puree, spices, salt, and pepper.
In a large skillet, heat the olive oil over medium-high heat. Add in the lentil and vegetable (Sloppy Joe) mixture. Sauté, stirring often until vegetables are softened and cooked through: about 7-10 minutes. Taste for seasonings and add more spices or salt and pepper if desired.
Serve the hot Sloppy Joe mixture on toasted buns, with bread, butter, and pickles.
Notes
This mixture would be fantastic served on rice as well. Think of it as a conduit for so many things- roll it up in a wrap, sandwiches, rice, almost anything. Bake in into a casserole and just serve it alone or as a side dish.