Entrees/ Gluten Free/ Healthy Eating/ Nut Free/ Vegetarian

Grilled Portabella Sandwich with Caramelized Onions and Goat Cheese

I am pretty much obsessed with my grill at this time of the year. There have been times this summer that I have used it every day of the week. There have also been days that I have used it for every meal of the day. While grills are mostly known for cooking meat, they can be used for many other things, like salads, desserts, breakfasts and breads. And of course, these items may not have any meat in them at all. Like one of my new favorites: Grilled Portabella Sandwich with Caramelized Onions and Goat Cheese.

Grilled Portabella Mushroom Sandwich with Caramelized Onions and Goat Cheese

I got the idea for these sandwiches in one of my favorite new cookbooks: America’s Test Kitchen Master of the Grill. If you ever grill, whether you are a total novice or an expert, I would recommend it. The book is divided into 3 sections: easy, moderate and advanced recipes. I have tried several of the easy (where I found their version of this recipe) and moderate recipes, but not yet ventured into advanced.

Grilled Portabella Mushroom Sandwich with Caramelized Onions and Goat Cheese

Actually today, I lost a little of my grilling confidence as I was attempting to grill roast a whole chicken. Following the directions was not working for me on my grill. The fat dripping from the chicken was causing some serious flare ups, and I ended up burning the skin and probably almost burning the house down. I wish I had taken a side by side picture of the beautiful picture in the cookbook and my blackened chicken beside it. Luckily it still ended up being edible. See, even food bloggers fail sometimes 😂

Grilled Portabella Mushroom Sandwich with Caramelized Onions and Goat Cheese

Anyway, these grilled portabella sandwiches shouldn’t result in any major fails as they are very easy. Two things to keep in mind:

1. Make sure you score the tops of the mushrooms. This keeps them from being too tough when you bite into them.

2. Don’t assume that all of your mushrooms will cook at the same rate. Whenever I buy portabellas, there always seems to be some big, thick ones and some skinny ones in the pack. The big ones will take much longer to cook.

If you already have some caramelized onions on hand (you can freeze them you know), you will be eating these delicious vegetarian sandwiches in no time!

Grilled Portabella Mushroom Sandwich with Caramelized Onions and Goat Cheese
Grilled Portabella Mushroom Sandwich with Caramelized Onions and Goat Cheese
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Grilled Portabella Sandwich with Caramelized Onions and Goat Cheese

This sandwich cooks up quickly if you already have the caramelized onions ready to go. It’s a meatless meal that’s sure to satisfy even the biggest carnivore.
Prep Time15 mins
Cook Time1 hr
Total Time1 hr 15 mins
Servings: 4
Calories: 432kcal


  • 2 teaspoons plus 3 Tablespoons olive oil, divided
  • 2 large onions, thinly sliced
  • salt and pepper
  • 4 portabella mushrooms
  • 4 ounces goat cheese, crumbled
  • 8 slices of bread or 4 rolls (use Gluten Free bread if you need this recipe to be Gluten Free)


  • Heat 2 teaspoons oil over medium heat in a nonstick skillet. Add onions and cook until they begin to soften and turn clear. Season with salt and pepper and reduce heat to medium low. Continue to cook, stirring occasionally until very soft and golden brown, 30-60 minutes. If onions begin to burn, add 1 Tablespoon of water a a time and/or reduce heat slightly. Remove onions from heat and set aside. Onions can be refrigerated in an airtight container for 3-4 days or frozen until ready to use.
  • Turn all burners on grill to high heat and allow to heat up for 15 minutes.
  • Pull of any stems from portabellas and scrape the brown gills from the underside of the mushrooms with a spoon. Brush or spray both sides of the mushrooms with olive oil and season with salt and pepper. Score the tops of the mushrooms in a grid pattern with a sharp paring knife, being careful not to cut all the way through the mushroom. Lightly brush both sides of bread or the insides of the rolls with olive oil.
  • Clean and oil grilling surface. Place mushrooms, underside down on grill. Grill until well browned and beginning to soften, 5-7 minutes. Flip mushrooms over. Add crumbled cheese to the mushrooms and cook until cheese is softened and the mushrooms are well browned and softened, 5-7 more minutes. Note that larger mushrooms will take longer to cook than smaller ones. Pile caramelized onions on top of the goat cheese and heat through, 2-3 minutes.
  • Remove mushrooms from grill and set aside on a platter. Place bread or rolls (insides down) on grill and grill for 1 minute (flip if using bread to grill second side). Place mushrooms on bread to form a sandwich.


Calories: 432kcal
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Grilled Portabella Sandwich nutrition info

Grilled Portabella Sandwich Nutrition Notes:

This meatless portabella sandwich is an excellent lower calorie alternative to a regular hamburger. However, the saturated fat content is on the high side, so if you’re looking to cut back, try to find lower fat goat cheese. I have had 4% goat cheese that tasted delicious, but it can be hard to find.

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