I've been making this for years, by adding a bit of this, a smidge of that. Today, I actually wrote all the ingrendents down. Any leftover meat can be used. The burros I made this evening were from leftover grilled beef steak and a marinated pork tenderloin. The taste of the orange marinade on the pork didn't come through at all, so no need to worry about mixing meats. If you are using leftover roast, you won't need to cook in the crockpot. If the chili isn't spicy enough for you, just add a pinch of cayenne while cooking.