Portabella Tuna Melts

I used to really enjoy tuna salad on white bread in my pre-keto life, but long gone are the days of reaching for highly-processed carb-loaded bread at the grocery store.  (Don’t get me wrong, bread is still delicious and I will indulge on vacations and some holidays throughout life, but it is a thing of the past in my everyday living.)  I was a bread fiend back in the day and just before converting to a ketogenic lifestyle I learned to make tuna melts panini-style on my George Foreman grill.  This version using portabellas  bring the same great taste and satisfying warmth of a traditional tuna melt without the unnecessary carbohydrates.

I started by pre-heating the oven to 350°F, lining a baking sheet with foil and spraying it with non-stick spray.  I also gathered all of the necessary ingredients as seen above.  For this recipe you want to use tuna packed in olive oil as opposed to water to raise the fat content, especially because tuna is packed with so much protein.

Next I cleaned the portabella caps with a damp paper towel and removed the gills with a spoon.  Mushrooms are very fragile, so you want to be gentle when removing the gills or you could easily break one of the caps.  The gills are soft and do not require much force to remove – gently scrape them away until both caps are gill-free.  I also pulled the stem off of each mushroom cap before placing them on the baking sheet.

I opened one can of tuna and drained the excess oil out before adding it to my bowl and topping with fresh ground pepper.  Feel free to add any other spices you want at this point.

Next I chopped the yellow onion and green onion.  I like my onion pieces a little larger in this, so it was just a rough chop.  The onion adds a nice crunchy texture to the otherwise soft tuna salad and mushroom, so my preference is to keep them larger and to include them raw.  You could saute them first in a little butter if you want less of an onion texture.  I also like both ends of green onions, so I included a bit of each for both color and flavor.  I added the yellow onion as well as the mayo to the tuna and mixed until everything was combined; leave out the green onions until the next step.

I evenly distributed the tuna salad mixture between the two mushroom caps and then topped with the green onions.  I then added half of the shredded monterey jack cheese over top of each mushroom cap before putting them in the oven for 15 minutes to let the cheese melt.  So simple, right?  This is a very easy week night meal to make as it takes hardly any time to prep and only 15 minutes in the oven.  The mushrooms shrink a bit as the water is expelled but they hold together wonderfully as a base for the tuna salad.  The onions stay firm and add the necessary bite to make this a complete meal.

Portabella Tuna Melts

Prep Time: 10 minutes

Cook Time: 15 minutes

Total Time: 25 minutes

Yield: 2

Serving Size: 1


  • 2 portabella mushroom caps (3oz each)
  • 1 5oz can of tuna, packed in olive oil
  • 3tblsp full fat mayonnaise
  • 1/4c chopped yellow onion
  • 2tblsp diced green onion
  • 1/2c shredded monterey jack cheese (can substitute cheddar)
  • Fresh ground black pepper, to taste


  • Pre-heat the oven to 350°F. Line a baking sheet with foil and spray with non-stick spray.
  • Clean and remove the gills and stems from the mushroom caps.
  • Drain the oil from the tuna and pour into mixing bowl; add black pepper.
  • Chop both the yellow and green onions; add the yellow onion to the tuna.
  • Add the mayo to the tuna and onions; mix thoroughly.
  • Evenly distribute the tuna salad between both mushroom caps; add the green onions on top.
  • Use 1/2 of the cheese on each mushroom.
  • Bake for 15 minutes until cheese is melted.

Nutritional Information

Per serving: 472 calories, 5g total carbs, 4g net carbs, 37g fat, 25g protein (Note: Please remember these numbers are based on the brands I used and may vary slightly with other brands.)

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