It's one of my favorites - rich beef-broth, savory onions, browned cheese... Yum. Luckily it is also one of the easiest things I make in our kitchen. The secret is in the slow cooker.
I never used to make french onion soup because I don't particularly enjoy caramelizing onions. The amount of slow stirring over the pan of onion aromatics... not really a cooking task for me. And then came the realization of Slow Cooker Caramelized Onions. Let me lay this out for you.
I say this is "almost instant" but in reality it takes a day or so to complete. However, most of that time is in the slow cooker, so it doesn't really count. You just have to think ahead a bit.
1) Throw some beef bones and about a quart and a half of water in your slow cooker the night before you want your soup. Add a potato for extra potassium if you wish it. Make sure the bones are covered with water. Turn it to high and leave it over night.
2) The next morning, pour the broth into a container to store in the fridge for the day. Discard the bones. Save the potato and have it for lunch. YUM.
(You can skip these two steps and buy a quart of pre-made beef broth at the store. But it won't taste quite the same.)
3) Slice up enough onions to OVERFILL your slow cooker. I use my food processor for this. You can do it by hand. Either way, you want enough to fill the slow cooker above the brim.
4) Add the onions and a stick or two of butter (8-16 oz.) to the slow cooker. I usually put half the butter in the middle, and half on top. Figure out how to lid this pile - I had to cover mine over with tinfoil this last time. Too many onions for the lid to fit!
**NOTE: If you don't want extra caramelized onions for later, fill your slow cooker only about half way with onions and reduce the amount of butter.
5) Turn the slow cooker back on (high). Leave it for the day. Stir it once or twice if you get the opportunity. Or just let it go. Whatever.
6) 20-30 minutes before you want to eat, open up your slow cooker. You should have lovely onions - a whole pile of them! Way more than you need for your soup. Take about 2/3 of the onions and freeze by the measured 1/2 cup on a cookie sheet or in muffin tins. Keep these guys in the freezer for caramelized onions in an instant. They thaw fast to be added to burgers, quiche, omelets, pasta sauce, whatever! That's a win. You can put them to the side and get them in the freezer after dinner or anytime in the next couple of hours.
**I am compelled at this point to bring up my dad's complaint with this method. You end up with caramelized onions that are more steamed than fried and therefore do not have the crispy caramel bits. I agree with him. I also like how simple it is to caramelize these guys.
7) Add the following to the remaining 1/3 of onions in the slow cooker:
Approximately 4 cups beef broth
1/2 cup (or more) dry white wine
4-5 fresh thyme sprigs or 2 tbl. dried thyme
Salt and pepper to taste
8) Lid the cooker and let it all warm up.
9) Serve the soup into oven-safe bowls. Top each one with some crusty baguette-type bread and slices of Gruyere cheese (Parmesan is okay in a pinch). Broil until the cheese is toasty and serve.
That's it. Lots of steps, but (with a food processor to cut the onions) no step takes more than 10 minutes. Most steps take more like 2 minutes.