Forget the Skillet—This Microwave Trick Gets You Great Onions Fast

Many years ago, my wife and I co-wrote a column for Reader’s Digest that told the compelling life story of a different ingredient each month (you have no idea how fascinating honey is). I always supplied a little recipe—just a simple, written-through thing that I had to squeeze into no more than a couple hundred words at the end of the column.

When it came time for us to cover onions, I encountered a recipe problem: The editors wanted a simple puff-pastry onion tart, but I knew the onions would need to be pre-cooked to soften them properly for the short baking time the recipe required. Under-cooked, leathery onions were not a result I was willing to settle for, but I didn’t have enough space in the recipe to write out a typical onion pre-cooking step in addition to the tart formation and baking.

That’s when a light bulb went off—could I use the microwave for this? I arranged my sliced onions on a microwave-safe plate, brushed them with oil, and zapped them for a few minutes. The result was perfect: Rounds of tender onion that had gently softened and turned every so slightly golden in the microwave—part steaming, part shallow-frying thanks to the oil. At that point, they were ready to go on top of the tart to finish roasting in the oven. It’s like a very gently sautéed onion, without the sautéing.

It’s a great technique—like sautéed onions without the pan, the mess, or the heat—and a worthy neighbor to other allium-microwaving methods, such as crispy fried shallots and garlic. The tart application is one of the best use cases for this method, but it’s far from the only one. You don’t have to limit it to sliced onion rounds; it can also work with onion slivers or wedges, diced onion, and more.

Here is the basic method, followed by some suggestions for incorporating it into your cooking for easier and quicker cooked onions.

How to Make Microwave-Softened Onions

First, find a microwave-safe plate: The oil will get very hot as the onions cook, and you don’t want the plate to shatter from the heat. Next, arrange your onions on the plate in an even layer and brush or toss lightly with oil to coat (olive oil or a neutral oil is fine). Sliced onions should not overlap (or overlap minimally), and diced or minced onions should not be mounded too high—try to spread them out on the plate in an even disk. If you want, you can season the onions with salt, or do so later as needed.

Next, microwave the onions on high power until they reach your desired level of softness. The timing will depend on how you cut the onions (i.e., the thickness and dimensions) as well as how thoroughly you want them to cook through. The timing will also vary depending on the microwave and its power level. I’ve found that 10 minutes is generally a good ballpark for thinly sliced onions that need to be very tender. Still, you may need less time or more—it’s best to microwave in two- or three-minute increments until you get a better sense of how the timing works in your microwave. For diced onions, you may want to give them a couple of stirs as well to ensure even cooking.

How to Put These Onions to Use

This method of quick-cooking onions has limitless potential applications—anywhere you may need some softened onion, this method may be helpful, especially given the speed, ease, and hands-off nature of it. Here are just a small handful of ideas to get the gears turning for you:

• In a quick onion tart. This is the application that inspired me to invent* this technique, and it’s a perfect example—solving a small technical challenge in a wonderfully low-effort and low-mess way.
• Tame onions for hearty salads. Many hearty salad and grain-bowl recipes call for raw onions, but the flavor can be harsh. At the same time, sautéing a skillet of onions to avoid a bit of that rawness is often more effort than most of us are willing to put in. Even a minute or two in the microwave using this method can take some of the sharp edge off while leaving the onions fresh and plump. Examples: tuna salad, grain bowls, bean salads, hearty vegetable salads, pasta salads, and more.
• Build a better onion to layer into toasts and sandwiches. Related to the salads idea above, sliced onion is a popular sandwich add-in. While some raw allium piquancy is sometimes just what’s needed, many a sandwich can be improved by adding the onion in a more tender, mellow form. While I wouldn’t describe these microwave onions as caramelized, they’re caramelized-adjacent in terms of application. Any toast or sandwich that would benefit from a caramelized onion layer would also pair well with these. I’d love to eat these with some salty anchovies on toast, or in a tender short rib grilled cheese, or a regular old grilled cheese, or a chicken salad sandwich, or a tuna melt, or so much more!
• As a lazy (but still delicious) side. Cut the onions more thickly and cook the slabs until just tender, and you have a nice little side to go with roast meats such as chicken, pork, beef, and lamb.
• As an easy add-in. Most of the time, if a recipe calls for sautéed onions, they’re prepared early in the cooking process before the rest of the ingredients are added and cooked. But there are moments when you may already be a ways down the cooking road when you realize you want to add sautéed onions to the mix, or perhaps you are deliberately leaving them out until the end so that they retain some of their plump texture in the finished dish. This technique is an easy way to prep the onions without having to get out a second pot or pan to cook them alongside everything else.

Those are just a few ideas to get you started. The key is this: Microwave-sautéing onions is a precision cooking method that produces soft and tender onions easily and quickly. After that, you can shove them in or on almost anything.

* I’m using “invent” loosely here; I’m sure I’m not the first person to have thought of this, but the idea was new to me when I came up with it.