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A purple plate on a tiled backdrop with caramelized onions and mushrooms with a golden spoon in it and slices of bread showing in the top corner.

Caramelized Onions and Mushrooms

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  • Author: Bianca
  • Prep Time: 10
  • Cook Time: 30
  • Total Time: 40
  • Yield: 4 1x
  • Category: side dish
  • Method: stove top
  • Cuisine: French
  • Diet: Vegan


Making perfect Caramelized Onions and Mushrooms takes just a few simple ingredients, yet the taste is pure decadence. They make the perfect topping or side dish.


  • 2 large onions, thinly sliced
  • 8 oz (about 225g) mushrooms, sliced (use your favorite variety)
  • 23 tablespoons olive oil or vegan butter
  • 12 cloves of garlic, minced
  • salt and pepper to taste
  • 1 teaspoon brown sugar (to help with caramelization)
  • 12 sprigs of fresh thyme or 1/2 teaspoon dried thyme (optional)
  • 1 tsp soy sauce (optional)


  1. Prep the Onions and Mushrooms:
    Peel and thinly slice the onions.
    Clean the mushrooms with a damp cloth or paper towel, then slice them.
  2. Caramelize the Onions:
    In a large skillet or pan, melt the butter or heat the olive oil over medium-low heat.
    Add the sliced onions and stir to coat them in the fat.
    Sprinkle a pinch of salt over the onions; this helps draw out moisture and aids in the caramelization process.
    Stir the onions occasionally. They will slowly turn golden brown and caramelize. This process can take about 20-30 minutes. You can add a teaspoon of sugar to assist in caramelization, but it’s optional.
    If you’re using fresh thyme, add the leaves from the sprigs when the onions are nearly caramelized.
  3. Cook the Mushrooms:
    Once the onions are caramelized, add the sliced mushrooms to the skillet.
    Increase the heat to medium and cook for about 5-7 minutes until the mushrooms are tender and have released their moisture.
  4. Combine Onions and Mushrooms:
    If you’re using garlic and soy sauce, add it to the pan at this point and cook for an additional minute until fragrant.
    Season with salt and pepper to taste. Remember that you’ve already added a pinch of salt to the onions earlier.
  5. Serve:
    Remove the skillet from the heat, and your caramelized onions and mushrooms are ready to serve. They are great with scrambled eggs, pasta, on pizza, sandwiches, or as a topping for burgers.


  • For best results, use a wide, heavy-bottomed skillet or wide non-stick pan. This allows for enough space for the onions and mushrooms to caramelize without overcrowding.
  • 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.
  • Take your time on low to medium-low heat. The gradual browning over time is what imparts that distinct sweetness.
  • Add garlic towards the end of the mushroom cooking stage. This prevents the garlic from burning and retains its aromatic flavor.


  • Serving Size: 4
  • Calories: 564
  • Sugar: 4 gr
  • Sodium: 50 mg
  • Fat: 54 gr
  • Carbohydrates: 28 gr
  • Fiber: 4 gr
  • Protein: 6 gr
  • Cholesterol: 0