Sweet, Sweet Sides
Get ready to elevate any meal with these caramelized onions and mushrooms! This side is easy to make, it just takes a little bit of time to get those perfectly, jammy onions and browned mushrooms. The onions come out a bit sweet, both from the natural sweetness onions have when they’re cooked, plus a pinch of sugar to help them along the way. Paired with the earthy flavor of mushrooms and subtle herb note from fresh thyme – it’s a match made in heaven! Eat them as a side on their own or as a topping for your entree. From steak, to salmon, to cheese, these onions and mushrooms will go with so many dinners!
The Supplies
Ingredients
To make this caramelized onion with mushrooms recipe, the following ingredients are required:
- Unsalted butter
- Olive oil
- Yellow and red onions
- Sugar
- Sherry cooking wine
- Baby portobello mushrooms
- Fresh thyme leaves
- Flaky salt, sea salt, and black pepper
For the exact ingredient amounts, check out the recipe card at the bottom of this page.
Equipment
In order to make this caramelized onion and mushrooms side, use the following pieces of equipment:
- Cutting board and knife
- Heavy-bottomed large frying pan (I recommend cast iron or stainless steel)
- Wooden spatula
Frequent Questions
Q: Can I make this recipe ahead of time?
- A: Yes! These caramelized onions and mushrooms can be made up to 2 days in advance. To reheat, microwave the onions in 30 second increments in the microwave. Stir the vegetables between each increment, until they’re warmed through.
Q: Does this recipe freeze well?
- A: Yes, it does! Freeze this recipe in an air-tight, freezer-safe bag or container. To reheat, defrost the onions in the refrigerator overnight. Once thawed, microwave the onions in 30 second increments in the microwave. Stir the vegetables between each increment, until they’re warmed through.
Q: What should I serve with caramelized onions and mushrooms?
- A: These onions are so flavorful they’ll elevate many different dishes! They would pair well on the side of a grilled steak or an oven roasted salmon. Serve them with a ball of burrata and toasty bread for an appetizer. Or, add them as a garnish to a bowl of tomato soup.
Recipe Tips
When you make these caramelized onions and mushrooms, here are a few tips to make sure they turn out great:
- The longer the onions are left undisturbed in the pan, the browner they’ll become. This leaves it up to the chef on how deep of a caramelization there is! If a deep, dark brown is desired, stir the onions less frequently. Doing so will lead to having some more bitter, charred notes to the onions. If a lighter color is desired, stir the onions more frequently. This will keep the onions sweeter.
- Don’t have any cooking sherry? For this recipe, you can substitute the sherry with balsamic vinegar, red wine vinegar, or a dry white vermouth.
- To ensure the best results, be sure to use a pan that’s on the heavier side. It will be more difficult to achieve an even caramelization in a non-stick pan or thin aluminum pan. Instead, opt for a cast iron or stainless steel pan and be sure to let it preheat before adding the onions.
Recipe Details
Caramelize the Onions
To get this recipe started, the first step is to melt a small knob of unsalted butter in a large, heavy bottomed frying pan over medium heat. Drizzle the olive oil into the pan with the butter and let it warm for 30 seconds. Swirl the two oils together and then carefully add the red and yellow onions in. Toss the onions to coat them in the melted butter and oil and let them cook on their own. The onions will begin to shrink and become translucent as they release their liquid.
Turn the heat under the pan down to medium-low and sprinkle sea salt and sugar over the onions. Toss to incorporate and cook a few minutes longer. The onions will develop a deep brown color during this stage, helped along by the addition of sugar.
Add the Mushrooms
Carefully pour the cooking sherry into the pan and stir to incorporate. Add the sliced baby portobello mushrooms and fresh thyme into the pan. Stir to incorporate the mushrooms into the onions. Let the mushrooms cook in the onions until they are tender and evenly browned, about 10 minutes more.
Finish the Caramelized Onions and Mushrooms
Remove the skillet from the heat. Taste the onions and mushrooms and season with flaky salt and pepper to taste. Enjoy right away, warm, with your favorite dinner. These would go great with a grilled steak or crispy chicken thighs. Store any leftovers in an airtight container in the refrigerator for up to 4 days.
If you make these caramelized onions and mushrooms, be sure to leave a comment or give this recipe a rating – I can’t wait to hear how it goes. As always, tag me on Instagram, TikTok, or Facebook in your photos. It makes me feel like we’re getting to cook together!
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Caramelized Onions and Mushrooms
Description
Caramelized onions and mushrooms that's sweet from the caramelized onions, earthy mushrooms, and dotted with pieces of fresh thyme.
Ingredients
Instructions
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Melt the unsalted butter in a large, heavy bottomed frying pan over medium heat. Drizzle the olive oil and let it warm for 30 seconds, swirling with the melted butter.
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Add the sliced yellow and red onions to the pan. Toss the onions to coat them in the melted butter and oil. Let the onions cook at medium heat, stirring occasionally. Continue to cook the onions until they reduce and become translucent, about 5 minutes.
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Turn the heat under the pan down to medium-low. Pour the sea salt and the sugar over the onions. Toss to incorporate and cook additional 7-8 minutes. The onions will develop a deep brown color.
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Carefully pour the sherry into the pan and stir to incorporate. Add the sliced baby portobello mushrooms and fresh thyme into the pan and stir to incorporate into the onions. Cook the mushrooms until they are tender and evenly browned, about 10 minutes.
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Remove the pan from the heat, taste, and season with flaky salt and pepper to taste. Enjoy!
