Portabello Tuna Melts

For great keto lunches, it can sometimes be hard—at least until you get the hang of it—to avoid bread when you get a sandwich craving. In this instance, though, portabello mushrooms are so, so much more flavorful than any open-faced sandwich has any right to be. Even better, it’s a quick recipe, so you can readily through it together on the go.


Category: Lunch Calorie Count: 644 (2 melts) Macronutrient ratio: Carb-induced calories—5% Protein: 39 grams Carbohydrates: 9 grams Total Fat: 51 grams
Prep Time 5 minutes
Cook Time 10 minutes
Total Time 15 minutes
Servings 2


Mushroom buns

  • 4 portabello mushrooms or other large flat mushrooms according to preference
  • salt to taste
  • pepper to taste
  • 1 tablespoon butter


  • 2 cans tuna drained
  • 1/4 cup mayonnaise
  • 2 tablespoons lemon juice
  • 1 celery stalk finely chopped
  • 2 spring onions sliced
  • 2 tablespoons chives chopped


  • 1 tomato
  • 4 slices Swiss cheese or other cheese as desired
  • 2 tablespoons olive oil


  • We're going to start by making our mushroom buns. Simply clean your mushrooms well with a damp paper towel, removing the stems, before seasoning with salt and pepper to taste, placing in a hot oven-safe pan greased with butter, cooking bottom-side up 1-2 minutes before flipping over, placing a lid on the pan to cover, and cooking an additional 5-7 minutes—until tender, but still firm—before removing from heat.
  • Next, make your tuna filling. Start by placing the drained tuna in a bowl, adding the mayonnaise, lemon juice, celery, spring onions, and chives. Mix well with a fork, seasoning with salt and pepper to taste. Meanwhile, preheat your broiler.
  • Make your topping by cutting the tomato into 4 slices. Set aside briefly. Next, divide your tuna mixture into 4 parts and spoon on top of each cooked mushroom. Top with a tomato slice and cheese slice before placing under the broiler for 3-5 minutes, just enough for the cheese to melt. Drizzle with olive oil and serve immediately.


Tools Needed:
  • Large oven-safe pan
  • Spatula
  • Serving plates

Leave a Comment

Your email address will not be published. Required fields are marked *

Recipe Rating