The inspiration for this gently sweet, uber-savory puree is a soubise, an old-school French onion-butter-cream sauce (it’s Escoffier old-school). We make ours with olive oil, lemon juice and water instead, and treat it as a spread or dip…and we’re wholly obsessed. We’ve slathered it on toast (it’s a vegan aioli of sorts) and topped it with grilled eggplant and salsa verde, or with roasted beets, raw and roasted carrots and dukkah, all to great success. We’ve been known to serve it as part of a plateau, too. If you want to use it as a sauce for pasta, it can be thinned with more olive oil and some pasta cooking water — and it’s marvelous (as in pasta with caramelized onions, roasted tomatoes and herbs). Onions, we salute you. (And we love you. A lot.)
Warm 2 tablespoons of olive oil in a very large sauté pan over medium-low heat. Add the onions and a sprinkle of salt and now…wait. Really, just wait. You’ll want to give the onions a good stir every 5-10 minutes or so, but making caramelized onions is really just about time. In a minimum of 45 minutes, possibly more, your pan’s worth of onions should have melted down to just over a cup’s worth of silky, sweet, rich onion strands. But don’t be hasty; if they’re not dark enough, they’re not truly caramelized…and that’s where the magic happens!
Once they’re nice and golden-brown, tip the onions into a blender and add another sprinkle of salt, a good bit of black pepper, two more tablespoons of olive oil, the lemon juice and the water. Drizzle in the remaining tablespoon of olive oil and more water, as needed, until you have a silky-smooth puree. (With our Vitamix, it works best to start on a low speed until the onions are really pureed, and then crank up the heat to get things airy and fluffy.) Taste and adjust flavor as needed — more lemon if you’d like it more lemony, more black pepper if you want more of a peppery kick, more salt if the flavor isn’t popping. What’s coming off your spoon should be sweet, savory and magically delicious.
Store in the fridge (it keeps for a week, at least) and slather on things with abandon.