In a food processor bowl, combine croutons, black pepper, cayenne pepper, chili powder, and thyme. Pulse until the mixture is of a fine texture. Place this mixture into a large bowl. Combine the onion, carrot, garlic, and red pepper in the food processor bowl. 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 combine thoroughly, but avoid squeezing the meat.