This Instructable will show how easy it is to render fat in a slow cooker. I used beef fat (suet) but the process is the same for any other animal fat. For a sense of scale: the photos included were using a 2 qt crock-pot, and the fat came from an untrimmed 12 pound brisket.
If you ask your butcher you can frequently get waste cuts of fat for dirt cheap. If you are on good terms with him/her you might even get them for free. You can also just trim the fat that you don't intend to eat off of cuts of meat (as in this Instructable). This untrimmed brisket cost about 1/3 of what trimmed brisket was selling for in the store. By putting in a little bit of work I saved money on the brisket, and ended up with all of the fat to render more or less for free.
If you have smaller pieces of meat you can trim the fat from them and store it in freezer until you have a large enough quantity to render.
Step 1: Trim Your Fat
You want to try and cut only sections of fat from the meat. It is inevitable that some fat sections will be marbled with meat and that is OK. Any meat that goes with the fat to render will turn into "cracklins" (similar to pork rinds/chicharron). I just throw the cut pieces into a bowl while I work. You can put the fat pieces in the freezer or refrigerator if you don't want to render them right away.
Be careful while you do this. Your knife is going to get greasy and become very slippery. Take your time and pay attention to what you are doing.
Step 2: Cut the Fat Into 1/2" Cubes
They do not need to be exactly 1/2" cubes, but I find that everything renders better if you have the pieces more or less uniform. Otherwise the big chunks will still be floating around when everything else has finished.
I have also found that it is MUCH easier to cut the fat pieces if you put them in the freezer for an hour or so before you begin. It firms them up and makes it easier to hold them down and less likely you will cut yourself. Whenever I am processing a large batch of fat to render I will take out a little bit at a time to chop up and leave the rest in the refrigerator/freezer.
Step 3: Start Rendering
Throw all of your cubes into the slow cooker and turn it on. The cook times for a 2 qt slow cooker that is completely full are:
- If you use the "high" setting it will need to render for about 20 hours
- if you use the "low" setting it will need to render for about 24 hours
Note: this is a general guideline. Sometimes it takes a bit more, sometimes a bit less. You are looking to see that the fat is all turning to liquid and the solid pieces are turning a golden brown. Once the solid pieces are getting dark the process is done.
I think the time to render for a larger slow cooker would be similar, but I have only used my small crock-pot for this.
You don't really have to do anything else while it is rendering. I like to check on it every 2 or 3 hours just to make sure everything is breaking down evenly and to see how far along it is. I usually give it a stir when I do this, but I find the smell while the fat is rendering to be unappealing when the lid is removed. I give it a quick stir and replace the lid.
Step 4: Strain Out the Cracklins and Let It Cool
Your tallow (or lard) has finished rendering and you just need to strain out the solids and let everything cool so you can use it.
I just use a simple wire strainer (similar to this) to strain the tallow into a bowl. All of the solid pieces are cooked and safe to eat. I don't care for them like this myself, but my wife and kids love them. I have to fry them for a few minutes and get them a bit crispy to enjoy them. You can also season them if you decide to cook them a bit more.
The last step is completely optional, but we have found it handy to pour the rendered tallow into cupcake molds. This makes it easier to store and easier to get fairly consistent amounts to cook with (some molds are a bit more or less full, but it comes out pretty close).