To render beef fat into tallow, ad a quarter inch of water to your pot (to keep the fat from burning, initially), then add the fat (preferably cut up into smaller pieces) and heat on a very low setting, stirring every 30 minutes to minimize sticking. The tallow melts out, separating from the cracklings (you are not cooking the fat, keep it below 170 degrees). Filter the still-hot tallow through a cheese-cloth over a colander, into a bowl. Allow to cool first before transferring into glass jars.
Tallow has a high smoke point and is more stable for cooking and frying.
brandon roepke –