These low carb Philly cheesesteak stuffed portobello mushrooms make for an easy but delicious keto dinner. The portobello mushroom caps are filled with all the flavors of a Philly cheesesteak but without the carbs of a bun! Make a big batch so you can have leftovers for a low carb lunch the next day. Each stuffed mushroom cap has only 4.5g net carbs and 260 calories!
You might also like this popular keto cheesesteak skillet using ground beef recipe!

Hi folks, this an updated post that I haven’t made in awhile. Stuffed portobello mushrooms have long been a staple in our family. I just love them and so does my hubby so it’s been a nice quick dinner during the summer months.
In the past I’ve made many stuffed portobello recipes because you can fill them with low carb toppings and the mushroom cap makes it easy for portion control. Today I am sharing one of my favorite easy dinner recipes: low carb Philly cheesesteak stuffed portobello mushrooms.
How Many Carbs In A Portobello Mushroom Cap?
I buy my portobello mushroom caps at Aldi and the average cap is about 3oz. In each cap there are roughly 30 calories, no fat, 2g net carbs and 3g of protein (source). So mushrooms are low carb, low calorie and make a great edible container for low carb dinners.
Portobello mushrooms are also rich in nutrients like potassium, folate, magnesium and zinc so if you like mushrooms, give this delicious and meaty portobellos a try.
How To Clean And Cook Portobello Mushrooms
Below you can see the underside of a raw portobello mushroom cap. To clean and cook a large portobello mushroom cap, you first take out the stem in the middle. You can chop and cook that with the rest of your filling or throw it away.
See the brown gills surrounding the stem? You want to clean those with a spoon. Just gently scrape them away. The gills are safe to eat but have a weird texture and most people clean them out.
Now in the bottom left picture above, you have your cleaned raw mushroom caps. Rub them with oil and turn the over with the topside up. This is because they will release a lot of water and it will just fill the cap if you cook them flipped over.
Bake in a 400°F oven for about 10-15 minutes depending on the size of your mushrooms. I checked mine at 10 minutes and they were not quite soft enough so I put them in another 5 minutes. They should be brown and soft enough to eat at this stage. Pour out any excess water before you fill them.
Let’s Make Some Keto Cheesesteak Stuffed Portobello Mushrooms!
The first thing you want to do is prepare your clean your mushroom caps and bake them in the oven. While they are baking, you want to cook the cheesesteak filling.
I used very thin sirloin steaks I found at Aldi. They were labeled “great for fajitas” in case you look for them. Chop the beef up into thin, small strips and the peppers and onions similarly.
Heat up the oil in a large saute pan and cook the onions and peppers for a minute or two and then add in the beef. Sprinkle some salt and pepper over the mixture and cook until everything is cooked through. This should take about the same time as the mushrooms to cook and cool.
Now all you have to do is fill up the mushroom caps and you can use the same cookie sheet the mushrooms baked on. Make sure to pour excess liquid on the cookie sheet and any in the mushroom caps.
Spoon the mixture into all of the caps and sprinkle some shredded cheese on top. I used mozzarella but you could use other cheese if you wanted. I think next time I might add a slice of provolone cheese instead. I’ll keep you posted!
Bake for about 10 minutes until the cheese is melted. If you want them to be browned on top you can also then stick them under the broiler for a few minutes. And that is all there is to it.
Save The Leftovers For A Keto Lunch
Believe me when I say the Philly cheesesteak portobellos were delicious. The meaty portobellos go great with the steak, onions and peppers and it was such an easy low carb dinner for my family. And since this recipe makes 8 mushrooms, we had leftovers for lunch the next day. I hope you enjoy as much as we do!
The nutritional information for 1 cheesesteak mushroom is:
260 cals / 15.4g fat / 7.2g carbs / 2.7g fiber / 21.7g protein = 4.5g net carbs
Low Carb Philly cheesesteak Stuffed Portobello Mushrooms
A quick and easy low carb meal that taste great! Philly Cheesesteak stuffed portobellos are filled with onions peppers and steak and topped with cheese.
Ingredients
- 8 large portobello mushroom caps
- 2 tablespoons of olive oil
- 1 lb of thin sirloin steaks, cut into thin, small strips
- 1 cup onion thinly sliced
- 1 cup  peppers thinly sliced
- 1 cup of shredded mozzarella
Instructions
- Preheat your oven to 400 degrees.
- Clean your mushrooms by scraping the gills off the underside.
- Rub oil on the tops and bottoms of the mushrooms and then place on a cookie sheet.
- Bake for 10-15 minutes until the mushrooms are soft and cooked through. Keep the oven on and take them out to cool. Drain any excess liquid off the tray and mushrooms.
- In the meantime heat up oil in a large saute pan. Ad in the onions and peppers and sauté for a few minutes until they start to soften. Add the steak and cook until everything is cooked through. This should take about the same time as the mushrooms bake and cool.
- Stuff the cooled mushroom caps with the steak mixture and then top with the shredded cheese.
- Set all mushrooms bake in the oven for 10 minutes. If you want them more brown on top just pop them under the broiler for a few minutes. Watch so they don't burn.
- That's it. These make a great low carb lunch the next day.
- NOTE: You can easily just half everything in this recipe to make just 4 servings.
Notes
The nutritional information for 1 cheesesteak mushroom is:
260 cals / 15.4g fat / 7.2g carbs / 2.7g fiber / 21.7g protein = 4.5g net carbs
Nutrition Information:
Yield: 8 Serving Size: 1Amount Per Serving: Calories: 260Unsaturated Fat: 0g
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