I read every post on eGullet and took each cook's advice into consideration before deciding on the following recipe and method:
Onion and Shallot Confit
1/4 cup olive oil
1/4 cup butter
3 tablespoons balsamic vinegar (you could swap this out with sherry or port or cognac or red wine)
1 tablespoon beef base (demi-glace would be better, or some reduced homemade stock)
1 tablespoon brown sugar
1 tablespoon pepper jelly (optional)
freshly-ground black pepper (to taste)
6 medium onions, peeled and sliced (ironically, the harsher-tasting the better, as they will yield the sweetest confit)
3 ginormous shallots, peeled and sliced (probably the equivalent of at least 6 regular ones)
*You may also choose to add some herbage such as thyme and/or bay leaves or even rosemary, but I wanted to keep mine simpler for this first attempt.
Add the olive oil, butter, vinegar, beef base, brown sugar, pepper jelly, and black pepper to the bottom of a crockpot set on high. Once the butter has melted, stir the ingredients together, and then add the onions and shallots. Mix until well-coated. Cover and cook on high overnight (about eight hours). You might be able to cook it all the way on high in less time, but after eight hours, I turned mine down to low and let it go another eight hours or until it reached a thick, jammy consistency, and a deep, brown color. After you eat a few spoonfuls and use some on whatever you're having for dinner, you'll end up with about a pint of the lovely stuff, which reportedly lasts a very long time in the fridge (but use a glass jar to keep everything else in the fridge from smelling oniony!).
Now that you have a pint of delicious and savory onions confit, what will you do with it? Well...it's Sunday night, which is often steak night here at my house. So I decided to season some ribeyes lightly instead of marinating or heavily rubbing them, as is normally my way. Then when they were seared but still quite rare, I topped them with a generous amount of the onion and shallot confit and some Danish bleu cheese and ran them under the broiler for two minutes. WOW! I served the steaks with some twice-baked style mashed potatoes, a potato mash that was augmented with a tablespoon or two of mayo and a couple of chopped green onions and a handful of shredded cheese with a little more cheese melted on top. Delish!
Below are some other ideas for using onions confit, pilfered from the eGullet posters. As you will see, you can use it on pretty much anything that would benefit from soft, sweet, richly-flavored, caramelized onions. So fire up that crock pot and get to slicing!
accompaniment to grilled meats
base for Alsatian onion tarts (pate brisee topped with onion confit, gruyere cheese, perhaps a few Nicoise olives, and/or anchovies)
accompaniment to baked brie or fried goat-cheese
heat up some canned beef bouillon and add a tablespoon of confit for "instant French Onion soup"
mixing a portion with some blue cheese (Stilton is good in this) and smearing it on a baguette
killer topping for pasta after adding some (more) balsamic vinegar
on a baked potato
in some sort of heavenly sandwich or a ploughman's lunch kind of thing, with some exceedingly ripe cheese
over scrambled eggs
with runny cheese, crackers, and a salad
with a crumbly cheese of some sort and pears
poached eggs crowned with the confit
as a topping for bruschetta
on a pissaladiere
on top of focaccia
portobello mushroom tarte tatin, optional chopped anchovies added near the end
atop a french bread slice, of which has been liberally spread with boursin cheese, and then topped with about a tablespoon of confit - toasted until the bread is crunchy
onion confit mixed with 2 tab of cream and 2 egg yolks as a filling for an onion tart
with pork chops
burgers off the grill topped with confit and sharp cheddar
on some rustic style pizza with roasted peppers and a sprinkling of gorganzola
over some smashed red potatoes with butter
with brie and crackers
a couple of all-beef hot dogs, lathered with a layer of onion confit along the bottom edge of a toasted roll, and the upper half topped with sauerkraut
as a garnish on some sliced-steak canapes
scoop of them spread over some rare london broil slices with some wonderful bleu cheese crumbles over top
duxelles in combination with the onion confit and shredded meat to make a filled bread roll
combine the onions with loads of garlic (perhaps up to several heads) and several crushed and chopped tomatoes... could take on a very nice garlicky, oniony, saucy texture
the onions, garlic, some cayenne, and maybe an assortment of fresh and dried chiles
in mashed potatoes
eaten by the spoonful!
*Follow-up: I found a new and wonderful use for this stuff. We had cube steaks for dinner, and I made the most delicious pan gravy using the onion and shallot confit. I whisked in a few tablespoons of flour into the pan drippings and added a couple of tablespoons of the confit. After I cooked this roux for a minute or two, I whisked in a cup of hot beef broth, and then once the sauce came together, I added enough half-n-half to reach a desired consistency. I seasoned it with salt and pepper, and that was it. It truly was the best gravy ever!