When you think about what the Western World use to be like pre-1950s, fat was an important ingredient to life.
Quite often, when engaging in historical cooking pursuits, be it reproducing recipes from the Middle Ages, American Civil War, or even war time cookery, you will find recipes calling for rendered fat. Here is a real simple way to render beef fat, albeit, it takes a very long time.
HOW TO RENDER ANIMAL FAT
For every pound of raw fat, place half a cup of water in the sauce pan (don't use your best sauce pan for this, it's a real bugger to clean). Place the pan on low, and lightly simmer with the lid off for many hours. Don't cook it too high or the fat will scorch and impart an unpleasant taste to whatever you cook with it. If the fat turns brown or smells scorched, toss the whole batch and do better next time.
When all the fat is melted, strain through a cheese cloth and leave the fat to cool before putting the lid on and storing it someplace cool (like the fridge).
I try to use this within 6 months. It will eventually go rancid sometimes after just a few months, sometimes it takes more than a year. You can smell it when it does, it's very distinctive.
I'm using beef fat that would have normally gone in the trash. After reading some WWII household manuals, I decided it would be nice to waste less. So instead of tossing out the fat and buying lard, I decided to render it down and use it to make meat pie crusts later this month. I don't normally have this much fat in one go, but I figure from now on, I can keep the little bits of raw fat I trim off roasts in a bag in the freezer, then when I have enough, I can render it.
I'm still not very good at trimming the fat off the meat, so there are a lot of bits of beef left over. Aim to do it better than I did, but if you are as rubbish at trimming raw meat as I am, don't stress over it.
I'm thinking of taking these left over bits of beef, trimming them up and putting them in a curry or possibly doing what my Great Grandmother would have done, toast them in a hot oven till crispy.
In Victorian days, they would have done this on a warm, but not too hot, part of the cook stove, for sometimes several days until the fat has completely rendered out. The stove is already being heated for other purposes, so it's not taking up a dedicated burner like me. I did mine on the electric stove, which wasn't the most economical method. I suspect a slow cooker would have been better, so I'll try that next time.