After rendering the excess skin and taking the drippings from the roasting, I’ve managed to fill a one-quart mayonnaise jar about 1/3 full. There’s another duck in the freezer, so I expect to get a similar amount from that one.
How long will rendered duck fat last in the freezer? Since it takes more than I can reasonably save to make confit duck legs, what are some good ways to use it?
Confit or no, it will make a great addition to a slow-cooked bean dish, like cassoulet. I don’t know about the shelf life.
Baste a goose? 
Placed in a sterilised container, it should keep for months in the fridge, without needing to be frozen. Grandmother kept duck and goose fat in cool larder.
I have had vats of duck fat in my 'fridge for going on three years. I’ve never bothered freezing it.
I use it in pie shells, to sauté vegetables, and to cook eggs. Also, duck-fat fried popcorn tossed with sea salt and fresh herbs is a lovely, lovely thing…
Well, the container isn’t sterile. It’s a glass mayonnaise jar that I washed (I do tend to be a little obsessive about washing dishes) and put the top on after they were dry.
Its fine and will keep for a long time. Months at least as long as you keep it refrigerated. Not sure about how freezing affects it though.
It’ll last for years in the freezer. And if you can get a sous-vide setup, you can can make confit with just a couple tablespoons of fat per leg.
It makes good hash, if you have leftover duck meat. Cook up some taters in the fat, add the duck meat and some onions and serve with a couple eggs on the side. Extra points if you use duck eggs!
If I have leftover duck meat! It’s only me, here! 
The reason I had duck for Thanksgiving is because I couldn’t face eating turkey for the next two weeks. Ducks have less meat, and are tastier than chicken. Even though I suck at getting meat off poultry carcasses, I do have a fair amount of meat left. The hash sounds interesting, but I think I’m just going to eat the duck as-is.
I might try frying some potato slices in it. I’ve heard that’s good. (I normally eat my potatoes chopped, grated, mashed, or baked.)
There is a restaurant in Chicago that sells french fries that are fried in duck fat. Yum.
You’re probably thinking of Hot Doug’s, a local hot dog joint. They have duck fat fries on Friday and Saturday. There’s a good number of other places in town that do it, too, (Franks N Dawgs, Sepia, the Portage, the Bristol, Custom House, onesixty blue, the Pump Room, etc.) but Hot Doug’s is the most well-known for it.
To be honest, I like my fries in beef tallow much more. Duck fat fries don’t wow me. However, sliced potatoes sauteed in duck fat–that’s a different story.
Duck fat makes the best roast potatoes. Parboil some floury potatoes, drain them but leave in the saucepan - add a couple of tablespoons of duck fat and shake the potatoes with it in the pan, with the lid on. Tip into a roasting pan and stick them in the oven until they’re crispy and golden. They’re fantastic.
If you have strained it - let it sit for a day or two, then skim the top of it and avoid what settles in the bottom; just keep it in the fridge and use it like butter. Some French bakers use it even in sweet pastries. If you spread it on hot toast it just disappears like gossamer.
Brushing it on baked vegetables or frying bacon and eggs in it is too obvious to mention I hope.
That place is amazing. The foie gras dog (duck sausage with foie sliced over it) is to die for. You can easily spend an hour in the round-the-block line at 2pm on a weekday though. I’ve taken some people who will refuse to wait that long “for a hotdog”.
I strained the pan-rendered fat through the sieve of my grease keeper into a measuring cup. It was clear, so I poured it into the jar. I did the same to the roasting-rendered fat. This had brown grit that was small enough to pass through the mesh. When it settled I poured the good stuff off the top into the jar, being careful not to let the sediment get in. Then I put a coffee filter over the jar and poured the rest in. I let it sit for a while (with the top screwed on) and discarded the couple of teaspoons of fat that couldn’t get past the sediment.
Luckily I can just buy mine at the supermarket from these guys (lots of great advice and recipes), but what you are doing will produce something the same or better.
Oh. I must stress. Fry an egg in it. You won’t believe how good it is.
I’ll have to wait before I do anything with the fat. I still have at least three servings of duck meat left after having eaten it for dinner and breakfast! Plus the duck-giblet gravy, garlic mashed potatoes, and green bean casserole.
I checked out the luvaduck site. They’re big on potatoes! I’m not a huge fan of roasted veg, mostly because I suck at it. (Why? Oil + Veg + Heat, right?) I don’t know about peeling and slicing potatoes after they’re cooked (sautéed potatoes). Seems they’d fall apart. I’m thinking I might slice the raw potatoes into thin discs using that side of the cheese grater, and just frying them in some fat.
This place (in the Portland on the other side of the continent) made its name on fries cooked in duckfat. I’ve had 'em and they’re sensational.
I love that place, but I sure as hell ain’t waiting in line that long for a sausage, either (and, lest you think I don’t appreciate it, sausage may just be my favorite food group.) I just go when there is no line (around 3:30 p.m., and there is a moment before the lunch rush where I’ve lucked in.) I’ve never been more than fifth in line at Hot Doug’s.
You only parcook them if you’re doing them sauteed in a pan. Here’s the method.
Or just slice the raw potatoes, stick 'em in a roasting pan with some onions, add salt, pepper, and your duck fat, and roast @ 425 until they’re done. You really can’t screw this up.