This Portobello Bunless Burger uses the mushroom caps as the "buns" around juicy seasoned ground beef, melted cheese, and crispy bacon. You can easily multiply the ingredients to make more than one burger, and switch up the cheese and other toppings to your liking.

  • CALORIES -- 771
  • FAT -- 67G (78%)
  • PROTEIN -- 38G (20%)
  • CARBOHYDRATES -- 4G (2%)
  • FIBER -- 1G

Portobello Bunless Burgers

These bunless keto burgers use portobello mushrooms as the "buns" and get a flavorful fat boost from crispy bacon and melted cheese.
Prep Time10 mins
Cook Time15 mins
Marinating Time30 mins
Total Time55 mins
Course: Main Course
Cuisine: American
Keyword: Burgers
Servings: 1
Calories: 771kcal


  • 2 large portobello mushroom caps (stems and gills removed)
  • 2 tablespoons olive oil
  • 1 tablespoon balsamic vinegar
  • 2 teaspoons salt (divided)
  • 1 teaspoon ground black pepper (divided)
  • 2 slices bacon
  • 4 ounces ground beef
  • 1/2 teaspoon garlic powder
  • 1/2 teaspoon onion powder
  • 1/2 teaspoon Worcestershire sauce
  • 1 slice cheddar cheese (or cheese of your preference)
  • 1 slice tomato
  • 1/4 cup mixed greens or arugula
  • 1 tablespoon reduced-sugar ketchup


  • Put the portobello mushroom caps in a bowl or shallow dish and add the olive oil, balsamic vinegar, and half of the salt and pepper; marinate for at least 30 minutes.
  • Cook the bacon in a skillet at medium-low heat until crispy, flipping over a couple of times to evenly cook each side. Set aside for later use as a topping.
  • Turn the grill on medium-high heat (about 200-300 degrees). In a bowl, mix together the ground beef, garlic powder, onion powder, Worcestershire sauce, and the rest of the salt and pepper. Form into a patty, ideally not quite as wide as the portobello “buns.”
  • Put the portobello mushrooms and the burger on the grill (you may need to do this separately if you are preparing multiple servings). Cook the portobello mushrooms for about 3-4 minutes on each side until they are soft and heated through. The burger will take about 5-6 minutes on each side for medium-rare. Put the cheese on the burger for the last minute of cooking to melt.
  • Assemble your burger with the bacon and the rest of the toppings between the portobello mushrooms.

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