Clearly, while I tagged this a venison recipe pretty much any ground meat will work here. Just make sure it has been ground with some fat or your meatballs will be sad and dry. Other than that, this is a dead-easy recipe. Only thing even remotely challenging is finding the chipotles in adobo, but every Latin market in America sells it, as do most larger supermarkets. In a pinch, you could buy chipotles in adobo online.
Put all the meatball ingredients together in a large bowl. Mix with your very clean hands until the mixture comes together. Don't overwork the mix or the meatballs will get tough. Roll into meatballs of whatever size you want. I like to make them by the tablespoon. If you have the time, let the meatballs sit in the fridge for up to an hour; this helps them stay together.
Brown the meatballs in the bacon fat, lard, or oil. Set aside once browned.
If you browned the meatballs in a large enough pan to hold all of them, drain all but about 2 tablespoons of the fat and keep using that pan. Otherwise, get a pot or pan large enough to hold all the meatballs and heat 2 tablespoons of fat in it. Cook the onions in this until soft and browned at the edges, about 10 minutes. Stir from time to time. Add the garlic and cook another minute.
Add the spices, chipotles, broth and tomato and mix well. Nestle the meatballs into the sauce and bring to a simmer. Simmer for about 20 to 30 minutes, until the meatballs are cooked through. Eat with rice or by themselves as an appetizer.
Serve this with rice, or by itself as an appetizer.