Finely rendered beef fat. Widely used in Argentinian cooking. The beef fat (suet) should be clean with only small amounts of meat on it. BTW, this is the type of fat that made the original McDonald's french fries so different. For 2 vegetable oil in a deep skillet, add 4 Tbs. of pella. You will be surprised at the difference.... A note on safety: You must watch this very carefully. Any time fat and water are combined, there is always the possibility of an explosion (of sorts.)Keep the heat steady, make sure your pan distributes it evenly and watch the process carefully. I have had the whole thing just go bloop and spray melted fat and water all over every surface in the kitchen. A clean kitchen is a nice thing, but not when it's because of an accident.