Beef-fat fries (how bad an idea is this?)
So, the 29-ounce can in the freezer into which I pour the fat I drain from hamburger and whatnot is full, and I thought: If I emptied this glop into my frying contraption to make a batch of pommes frites, would that give me some approximation of the vaunted beef-tallow fries? (I imagine there will be some degree of topping-off with peanut oil.)
Is this a horrible idea? There's probably a small percentage of lamb and maybe chicken fat in there as well -- and I'm not entirely sure whether solidified ground-beef runoff qualifies as "tallow" or not.
You should clarify it. Heat it up, skim any scum, boil off any liquid (could be very messy and a fire hazard), pour the liquid fat through cheesecloth, stop pouring when you get to the particulates at the bottom.
If it's pure fat, sure, that should work great, but if, as Robert pointed out, it's fat + meat juices, that will take some more work. If you have time, the easiest method for clarifying it would be to bake the can until the fat is hot/liquid, let it cool, chill it, and then take the solid fat off the top and use a paper towel to blot off any liquid.
And, maybe there's other opinions on this, but if you're going to save fat from different animals, I'd save it separately. I know French onion soup can be a combo of chicken and beef stock, but generally speaking, I don't find the two flavors that complementary. Lamb is a little closer to beef, but lamb fat is where most of the gameyness resides, so it might not be that worthwhile saving.