Caramelizing onions is one of those things no one thinks you need a recipe for. Just cut them up and cook until caramelized, right?
Except most recipes call for caramelizing your onions for 10-12 minutes. Or 15-20 minutes. Which, my friends, cannot be done.
You can brown them in that time and achieve some nice color, but you're really just singeing the onions. Or, if they have enough time to start releasing, singeing the onion's natural sugars. And once that happens, it's impossible to achieve that depth of flavor that only comes from truly caramelizing your sugars.
For true, jammy, flavor-bombs of caramelization, follow the instructions below. And be prepared to spend at least 45 minutes. It takes time for these sweet alliums to release their sugars and for those sugars to cook. They're worth it.
We put these in our classic grilled cheese.
2 to 4 large yellow onions
2 tablespoons unsalted butter or olive oil (This is one instance where I like butter)
1/4 cup white or red wine or balsamic vinegar
1/2 teaspoon kosher salt
1. Top and tail your onions, leaving the roots intact. Slice in half the longways (through the root) and cut each half into half moons.
2. Melt 2 tablespoons unsalted butter in a large skillet over medium-low heat, or heat 2 tablespoons olive oil until shimmering.
3. Add the onions and stir to coat with butter or oil.
4. Cook the onions, checking on them every 5 minutes. When you check, give them a stir to scrape up any of the bits that are sticking to the bottom. These are the fonds, or sweet bits of sugar where the flavor is just starting to form.
5. The first benchmark you're looking for is the onions softening and turning translucent. This usually takes around 10 minutes. Give them another stir, mix in those fonds, and keep going.
6. Soon, your onions will begin to get very soft and will break apart if you push on them with your wooden spoon. This is good! They're breaking down and letting out their sugar. You might even see some legit brown spots and being to smell caramelization. This is the time to lower your heat if you notice any scorching.
7. Soon your onions will be sporting a unified blonde shade, right around the 30 minute mark. Give another stir and scrape the bottom to get those fonds mixed in.
8. About 10 minutes later, your onions should be the color of dark toast and smell like heaven. Give them a taste. Are they soft and sweet enough for you? They might be, but I like to go another 5 minutes or so.
9. Once you're at your desired doneness, pour in your wine or vinegar to deglaze the pan. The liquid will hiss and steam, and you can use that energy to scrape up any last fonds and swirl them into your onion mix. Season to taste with salt.
10. You're done! Store, refrigerated, for up to 1 week, or cool and freeze for up to 3 months.