Begin by browning your meat in a large pot. Once you have thoroughly browned your meat, remove to a bowl with a slotted spoon. Remove the fat drippings as well.
Add the canola oil, bring back to medium heat, and toss in your carrots, onion, garlic, celery, bell peppers, and chili flakes, and cook on medium heat for about 7 minutes or until the vegetables have softened.
Add the ketchup, tomatoes, tomato puree, Worcestershire sauce, vinegar, chipotle peppers, adobo sauce, and brown sugar. Mix well. Season with salt and pepper and give it another stir.
Cover, and cook on medium to low heat for about 15 minutes. Toss the sauce into a food processor, or blender, and puree it into a nice smooth sauce. Add the sauce back to the pot, reduce heat to low, and add in the cooked ground beef. Give a nice stir, and cover.
Cook for about another 10 minutes. You are now good to go on making the sloppy joes.
To make your sandwich, take one of your hard rolls and stack on the sloppy joe mixture. Add a layer of fritos, and top with the other bun. I went this route on as I wanted a bit more texture and that crunch and additional spice from the chili fritos was just perfect. The chipotle sloppy joes were still a winner with my kid and they were just spiced enough that everyone could enjoy.