In the bowl of a food processor, combine the croutons, black pepper, cayenne pepper, chili powder, and thyme, and pulse until finely ground. Place this mixture into a large bowl. Add the onion, carrot, garlic, and red pepper to the bowl of the food processor, and pulse until the mixture is finely chopped, but not pureed. Combine the vegetable mixture, ground sirloin, and ground chuck with the bread crumb mixture. Season the meat mixture with the kosher salt. Add the egg and, using your hands, combine thoroughly, but avoid squeezing the meat.