Marinated Portobello Mushroom Burger with Fried Egg, Goat Cheese, Spinach, & Caramelized Red Onion
Prep time
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When wanting to add more veggies into your routine, a Marinated Portobello Mushroom Burger with Fried Egg, Goat Cheese, Spinach, & Caramelized Red Onion, is the winner. Marinating the portobello mushroom allows it to soak up so much flavor for a rich, juicy, hearty vegetarian burger. Portobello mushrooms also have vitamin D. The kicker is the fried egg on top which adds to the burger’s gooey decadence as the yolk slowly drips into your mouth. Eggs are packed with omega-3s, vitamin D, and other powerhouse nutrients, making this dish the tastiest, nutrient-rich mushroom burger. You won’t even need any condiments. *I used a panini maker to grill the portobello mushrooms in my kitchen.
Recipe type: Sandwich
Cuisine: American
Serves: 4
  • 4 portobello mushroom caps
  • 2 Tbsp extra virgin olive oil (divided)
  • ½ red onion, sliced
  • 8 ounces baby spinach
  • 4 large eggs
  • 4 ounces goat cheese
  • 4 hamburger buns
  • Salt and pepper to taste
  • Marinade:
  • 1 Tbsp extra virgin olive oil
  • 4 Tbsp balsamic vinegar
  • ¼ tsp oregano
  • ¼ tsp garlic powder
  • ¼ tsp onion powder
  • 1 tsp paprika
  • salt and pepper to taste
  1. In a small bowl, combine all the ingredients for the marinade including the olive oil, vinegar, oregano, garlic powder, onion powder, paprika, salt, and pepper, and whisk.
  2. Put the mushrooms in a gallon plastic bag or glass container and add the marinade. Marinate in the fridge for at least 1 hour or overnight.
  3. In a medium pan over medium heat, add 1 Tbsp of the olive oil. Sauté the red onions and slightly caramelize for about 4 minutes.
  4. Add the spinach. Season with salt and pepper. Sauté for about 1-2 minutes.
  5. Remove from heat. Put the onions and spinach into a bowl.
  6. Using the same pan, add the other 1 Tbsp of olive oil. Over medium heat, heat the oil. Crack 2 eggs into the pan at a time and let the eggs cook for about 2-3 minutes.
  7. While the eggs are cooking, slightly move the pan to distribute the oil onto the eggs. Towards the end of the 2 minutes, flip the egg over briefly just to cook the yolk a little.
  8. Transfer the eggs to a plate and cook the other 2 eggs in the pan. You may need to add a little more oil.
  9. Over a grill or using a panini maker or George Foreman grill, remove the mushrooms from the bag and grill them for about 3 minutes on each side if using a grill. If using a panini maker or George Foreman, grill for 3 minutes total since each side will be cooked at the same time. Remove from the grill. I also use the leftover marinade from the mushrooms to put on the buns as a “dressing.”
  10. Make the burger. You can toast the bun in the oven with the cheese to melt it slightly. Add the portobello mushroom to the bun. Top with the cheese and then the spinach and onion mix. Add the fried egg on top. Enjoy.
Nutrition Information
Serving size: 1 Burger Calories: 339 Fat: 20.8 Saturated fat: 8.2 Carbohydrates: 17.8 Sugar: 4.2 Fiber: 2.8 Protein: 19 Cholesterol: 158.4
Recipe by Sarah Koszyk at