Caramelized Onions and Mushrooms

This perfect Caramelized Onions and Mushrooms recipe is an excellent topping or hearty side dish. With only a handful of ingredients, these caramelized onions and mushrooms are easy to make and incredibly delicious.

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⭐️ Why you should try this recipe

• This heavenly combination is not only delicious but also incredibly versatile.
• Due to the long cooking time on low heat, the texture of the mushrooms becomes irresistibly soft, making this recipe a must-try even if you are not a fan of mushrooms.
• Easy to make ahead for Thanksgiving or Christmas. 
• These mushrooms with onions are a great side dish, topping, or addition to a sandwich or burger.

📘 What is caramelize in cooking?

Caramelization is a cooking process that involves heating sugars in the presence of heat, causing them to break down and undergo a series of chemical reactions. For example, in this recipe, the sugars present in the onions undergo this process when exposed to low-heat over an extended period. As the sugars caramelize, they develop a rich, golden-brown color and a complex, sweet flavor.

This slow-cooking method enhances the onions’ natural sweetness and adds depth and complexity to the dish, creating a savory-sweet flavor profile.

🍄 Ingredients

• Onions: Onions’ natural sugars intensify during cooking, contributing to the rich taste and deep color of the dish.
• Mushrooms: Mushrooms, such as button mushrooms, add a delightful umami flavor to the caramelized onions. They absorb the savory juices during cooking. 
• Olive Oil: Olive oil is the cooking fat, providing a smooth and light texture to the dish. 
• Sugar: A small amount of sugar helps to caramelize the onions, accelerating the browning process and intensifying their natural sweetness. It helps achieve that golden-brown color.
• Garlic: Adds a robust and aromatic flavor.
• Thyme: Fresh or dried thyme adds earthy and herbal undertones to the caramelized onions and mushrooms. 
• Salt and Pepper: Salt is added to the onions to draw out moisture, aiding caramelization and enhancing flavor, while pepper adds a subtle kick.

🥣 Substitutions and Variations

Feel free to experiment with substitutions and variations to suit your taste:

• You can use red, yellow, or white onions, but sweet onions are ideal for a deeper caramelization.
• Feel free to use your favorite variety of mushrooms or a mix. Some great options are:
  Button Mushrooms: These mushrooms have a mild flavor and a delicate texture. While not as robust as cremini or shiitake, they can still contribute a pleasant taste to the caramelized mix. Button mushrooms are a good choice if you prefer a milder mushroom flavor.
  Baby Bella Mushrooms (Cremini). These are a more mature version of button mushrooms and offer a deeper, earthier flavor. They have a firmer texture and can hold up well to the caramelization process.
  Shiitake Mushrooms: These are known for their umami-rich flavor; shiitake mushrooms have a meaty texture that complements the softness of the onions.
  Portobello Mushrooms: With a meaty and substantial texture, portobello mushrooms have a mild, slightly sweet flavor.
• If you prefer a rich, buttery flavor, use vegan butter instead of lighter olive oil.
• Enhance the flavor by adding or substituting more flavors, such as soy sauce (can highly recommend!), rosemary, oregano, parsley, or red pepper flakes. Experiment with what you like, but keep it simple. 

🥣 How to make caramelized mushrooms and onions (step-by-step with photos)

Step 1: Prep the Onions and Mushrooms
Peel and slice the onions. Clean the mushrooms with a damp cloth or paper towel, then slice them.

Step 2: Caramelize the Onions
In a large skillet or pan, melt the vegan butter or heat the olive oil over medium-low heat.
Add the sliced onions, stirring to coat them in the fat. Sprinkle a pinch of salt over the onions and stir occasionally so they can caramelize over 20-30 minutes. Add a teaspoon of brown sugar (to help with the caramelization) and the thyme.

Step 3: Cook the Mushrooms
Add the sliced mushrooms to the skillet. Cook for about 5-7 minutes until the mushrooms are tender and have released their moisture.

Step 4: Combine Onions and Mushrooms
Add the garlic. Season with salt and pepper to taste (keep in mind the pinch of salt added to the onions earlier).

Step 5: Serve
Remove the skillet from the heat, and your caramelized onions and mushrooms are ready to be served.

Make sure to check the recipe card for the full recipe with the exact quantities and information on all the ingredients.

📔 Tips

• Choice of Pan: Opt for a wide, heavy-bottomed skillet or pan. This allows for even heat distribution and enough space for the onions and mushrooms to caramelize without overcrowding.
• Low and Slow: It is important to take your time on low to medium-low heat. This slow process will help the natural sugars to caramelize slowly, resulting in a richer flavor and golden-brown color and avoiding burning the onions or uneven caramelization. The gradual browning over time is what imparts that distinct sweetness.
• Onions First: It is important to cook the onions first and to add the mushrooms only after the onions are caramelized. This helps prevent the mushrooms from releasing too much moisture.
• Garlic Last: Add it towards the end of the mushroom cooking stage. This prevents the garlic from burning and retains its aromatic flavor.

❔ How to Store Caramelized Onions and Mushrooms

While hot and fresh caramelized onions are best, letting them sit for a few days and then reheating them can actually improve the flavor. 
You can refrigerate them in an airtight container for up to a week or freeze them for a few months.

• Refrigeration: Allow the caramelized onions and mushrooms to cool to room temperature before transferring them to an airtight container. Refrigerate for up to a week.
• Freezing: For longer storage, consider freezing the caramelized onions and mushrooms. Place them in a freezer-safe container or a zip-top bag. They can be frozen for several months.
• Reheating: When ready to use, thaw frozen caramelized onions and mushrooms in the refrigerator overnight. Reheat them in a skillet over low heat, stirring occasionally until warmed through.

💬 Frequently Asked Questions

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