Caramelized Onion & Blue Cheese Burgers

Dig into these fully loaded burgers with caramelized onions and blue cheese served on portobello mushroom caps.

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Both beef and onions are a source of sulfur, an important element for blood sugar management and hormone regulation. Beef and mushrooms are also rich in zinc, a mineral that supports thyroid health.

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Prep Time
45 min
45 min


  • ¼ cup avocado oil, divided

    1 tbsp organic unsalted butter

    1 large sweet onion (such as Vidalia), thinly sliced

    1⅛ tsp sea salt, divided

    4 portobello mushroom caps, gills scraped out

    1 lb ground beef

    ½ tsp ground black pepper

    4 leaves green leaf lettuce

    1 oz crumbled blue cheese


  1. In a large skillet on medium, heat 1 tbsp oil and butter. Add onion, season with ⅛ tsp salt and cook 1 to 2 minutes, stirring occasionally. Reduce heat to medium-low; cook, stirring occasionally, until onions are soft and deep golden brown, 20 to 25 minutes. If needed, add water, a few tbsp at a time, to prevent sticking. Transfer onions to a plate; cover and set aside. (NOTE: Do not wipe out skillet.)
  2. Meanwhile, preheat oven to 400ºF. Line a large baking sheet with parchment paper. Brush mushrooms all over with 2 tbsp oil; season with ½ tsp salt. Place mushrooms, stemmed side up, on baking sheet; roast until tender, 10 minutes. Using tongs, flip mushrooms, discarding any liquid that has accumulated. Roast 10 to 15 minutes longer, until very tender and lightly browned. Reduce heat to 200ºF to keep warm.
  3. Divide beef into 4 equal portions; press beef into patties, about ½ inch thick. Season with pepper and remaining ½ tsp salt.
  4. In the same large skillet on medium-high, heat remaining 1 tbsp oil. Cook burgers 3 to 5 minutes per side, until browned and cooked to desired doneness.
  5. Divide mushrooms among plates, stemmed side up. Top each with lettuce, a burger patty, caramelized onion and blue cheese.

Related: Double Mushroom Burgers with Cheddar & Umami Mayo

Nutrition Information

  • Serving Size 1 burger
  • Calories 396
  • Carbohydrate Content 12 g
  • Cholesterol Content 80 mg
  • Fat Content 28 g
  • Fiber Content 2 g
  • Protein Content 25 g
  • Saturated Fat Content 9 g
  • Sodium Content 646 mg
  • Sugar Content 7 g
  • Monounsaturated Fat Content 14 g
  • Polyunsaturated Fat Content 2 g

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