A few weeks ago, I was catching up with my sister over the phone. I don’t get to chat with her often since she’s a mother to two beautiful kids under 3 and to two charming pups and lives in Austin, TX—so this was a real treat! Somehow, the conversation turned to meal prep.
We were talking about slow-cooker meals, and she said they’re a huge time-saver for her—except that often, you still have to end up dicing and sautéing before you put your ingredients in there! Although you can dice and chop veggies ahead of time when you get back from the grocery store to keep refrigerated and ready to go for the week, that doesn’t save you too much time if you’re still browning carrots and sautéing onions before you load up your slow cooker.
I mentioned that at least with garlic you can roast it in batches ahead of time to store for later—and she asked, “Do you think you can do the same thing with onions?” And thus, an idea was born.
As it turns out, the answer is yes! Most methods for roasting garlic tell you to slice off the top of the head of garlic, wrap the whole thing in foil, skins and all, and roast—however, you can do use the same process with pre-peeled garlic cloves. I figured I’d try the same concept with onions.
I diced mine, since that’s how I most frequently use them in recipes, although you could just slice or roughly chop, depending on what you make with your onions. I only had 5 medium onions, so that’s what I used. Once diced, this turned into approximately 3.5 cups. I doused this in 2-3 tablespoons of olive oil (enough to coat the onions) and sprinkled salt over all of them, and wrapped that in aluminum foil. The foil package went in the oven (preheated to 400°F).
I checked on the onions after about an hour when the whole house started smelling sweet and delicious, but it needed more time. (Timing depends on how caramelized you want your onions.) I ended up leaving the foil package in the oven for 1.5 hours, then kept them wrapped in the foil until they cooled.
This resulted in approximately 2.5 cups of caramelized diced onions. You can refrigerate this in a tightly sealed container for up to a week. Or freeze the rest. I put some in greased muffin tins to freeze about 2/3 cup servings for future recipes. I let that freeze overnight, then popped out my frozen onions, wrapped in plastic wrap, and put that in a freezer bag to store. You could also freeze smaller amounts in an ice cube tray or in a thin layer on a baking sheet (easy to break up for scooping once frozen).