Sweet and jammy caramelized onions make a beautiful pairing with quick-seared and savory mushrooms. They're the perfect topping for latkes of any kind, filling for omelets and swimming in the center of a grilled cheese sandwich. Caramelized onions and mushrooms are your new go-to BFF.
They may be the perfect pair that present endless serving possibilities, but caramelized onions and mushrooms are the the culinary odd couple takes very different paths to that celestial caramelization destination.
For onions, the path is low and slow. No crispy brown bits or edges. Just mellow, melting slices of allium cooked over very low heat, perfect for almost any appetizer or topping.
For mushrooms, the path is hot and swift. After clearing the pan of the beautifully caramelized onions, the mushroom pan is heated up considerably and the shrooms are seared for about 3-4 minutes - less than one tenth of the time it takes to caramelize onions. The quick sear in the hot pan with oil creates a gorgeous golden brown crust on the mushrooms which is the hallmark of intense, earthy flavor.
It's an easy recipe that's a culinary adventure worth twice the price of admission!
Here's what you'll need to make caramelized mushrooms and onions:
Step by step process for making caramelized onion recipe with mushrooms:
Begin my peeling and slicing 3 yellow onions. I like to cut my onions in half, then lay the flat side down on the cutting board so all of my slices are half moons. I recommend about ⅛-1/4 inch thin slices - thin enough to cook through but not so thin as to risk burning or browning.
Melt two tablespoons of butter with one tablespoon of olive oil in a large saute pan or cast iron skillet. Add the sliced onions to the pan and stir quickly to break up the onion rings and coat the thin strips in butter. Return to a low heat burner. Let the onions cook over that low heat, stirring from the bottom of the pan every few minutes. Monitor the heat to ensure the onions are not sticking or browning, as they do when you're making sautéed onions.
After 15 minutes, this is what they look like - slightly softened and yellowing. This is when I usually add a pinch of salt to the pan.
After 30 minutes, this is what they look like - the deeper caramelization is coming around the edges.
And here is the completed dish at the end of cooking - about 50 minutes over low heat completes the caramelization process.
Transfer the sweet onions to a separate bowl and set aside.
While the onions are caramelizing, clean and slice 8 ounces of baby bella mushrooms. Use a damp paper towel or a cloth towel to clean the mushrooms. Do not rinse under water, or the wet mushrooms with their excess liquid will struggle to brown.
Heat oil (1 tablespoon of olive oil) over medium high heat. Add the sliced mushrooms to the large skillet in a single layer (to the extent possible).
Cook for about 3-4 minutes and do not disturb the shrooms. Leave them untouched. Mushrooms contain a lot of water. You'll see them release their water, steam briefly, then dry up and caramelize. When the pan dries and the mushrooms are sizzling, toss the mushrooms to ensure they have taken on the caramelized brown color.
Remove from heat. Add a pinch of salt - less than a quarter teaspoon salt, a few cracks of black pepper and the fresh thyme leaves.
Then add the caramelized onions back into the pan and toss.
Taste and adjust seasoning. Plate, top with additional fresh herbs, and serve.
FAQ's about caramelized onions and mushrooms:
Time and heat level are the two factors driving the difference. Sauteed mushrooms and onions are usually cooked over medium heat to medium-high heat and you're looking for browning and crisping on the onions. Usually the mushrooms don't brown, because the liquid released from the onions are absorbed by the mushrooms, so they cook, but don't brown.
This is a versatile dish and almost any onion variety will work here - I've recommended yellow but white, sweet Vidalia or red will also be good options that offer great flavor.
This is one of my favorite recipes to make almost weekly, so I've made it often enough to know that baby bellas are the best mushrooms for the mix. But white mushrooms are perfectly acceptable, and I've even used a mix of wild mushrooms which added a real depth of flavor to the dish.
Of course! I'm a huge fan of mushrooms, onions and thyme (hello, French onion soup!) so that's my preference. But fresh parsley would add a nice, fresh hit of herby flavor, as would rosemary. If I'm out of fresh herbs, I have added a pinch of dried poultry seasoning and it has been delicious. Fresh herbs may add the best flavors, but that spice drawer almost always has a savory flavor solution, right?
You certainly could do that but the mushrooms will have a really hard time getting that brown caramelization. This method will achieve that sweet, jammy onion AND the crispy-edged mushroom, which takes the dish to a whole new level of flavor. This is a simple recipe with just a few ingredients, I like to treat each one really well to coax the most flavor out of them.
It's an easy dish that brings so much flavor, so the pairing options are practically endless. A few of my favorites include:
- topping mashed potato latkes along with sour cream dill sauce
- vegetarian option for omelet filling
- gourmet ingredient for grilled cheese sandwiches
- easy side dish for grilled fish and rice
- healthy addition to grain bowls
- easy add-in for quiche
- versatile side dish for any protein (pescatarian, or not!)