This recipe is meant for regular pork, but you can make it with most meats -- just make sure you have between 20 and 35 percent fat by weight. If you can't find a cool green powder like the nettle powder, you can add a little green food coloring. It makes about 5 pounds of sausage, and can be scaled up.
Cut the pork shoulder into chunks that will fit in your grinder. Mix with the salt and put in a closed container in the refrigerator overnight. Doing this helps develop myosin in the meat, which helps your sausage bind to itself.
The next day, put all your grinding equipment in the fridge, and the blade and a 6.5 mm (or medium) die in the freezer. Take out about 15 feet of hog casings and flush them with warm water, checking for leaks. Set the casings aside in a bowl of warm water.
Put the roasted green chiles, cilantro, serrano chile, and the garlic cloves in a food processor and buzz until you have a fine mix, almost a paste. Mix that in a bowl with the oregano, cumin, and coriander. Put it in the fridge.
Grind your meat through the grinder once or twice. Once if it's decent pork shoulder, twice if you are using gnarly bits. Set the ground meat in the freezer while you clean up the grinder and set up your sausage stuffer.
In a large bowl, mix the meat, the chile mixture, the nettle or spinach powder, if you are using it, as well as the carrot fiber, lime juice and ice water. I do this with my (very clean) hands for about 90 seconds, until I can't stand it any longer; your hands should ache with cold while you are mixing. You want the entire 5-pound batch to stick to itself in a messy, sticky ball when you pick it up.
Put the loose sausage in a stuffer if you are making links, or make patties if you want it loose. To make links, thread a casing onto the stuffer tube and leave about 3 inches of casing at the end. Fill the entire length of casing fully but not too tightly. Repeat until you have filled all your casings.
To make links, starting from one end of the coil, pinch off about a 6-inch link at the end with one hand, then another by using your other hand. Roll the second link away from you about 5 times to form the link. Compress the end link with your hands and tie it off. Now move down the coil and pinch off two more links. This time you want to roll the link farthest from the end of the coil towards you about 5 times. Continue this with all the coils. Tie off the final link on the other side of the coil. Forming links this way keeps them from unraveling too easily.
Use a clean needle or sausage pricker to piece the casing where there are air pockets. Gently compress each link to push out the air. Let your links hang for at least 1 hour on a drying rack, or whatever you can rig up. Ideally you'd let them hang overnight in a refrigerator, but even an hour's worth of room temperature air will help the sausages bloom and fill their casings.
Regardless, store your chorizo overnight before vac sealing and freezing. They will keep in the fridge a week or so.