What is the difference between a portobella mushroom, a cremini mushroom, and a white button mushroom (all of which are readily available at your local produce market)? Nothing…except maturity, and perhaps as much as $3 or $4 per pound. They are the same species – just harvested at different stages of their growth cycle. But unless you are planning a dinner party and want hors d’ oeuvres, the extra price to buy about six mature portobella mushrooms for this recipe is well worth the reduced prep time compared to hollowing and stuffing about twenty or more of the smaller variety.
We’re going to stuff these with a mixture of spinach, ground beef, tomatoes, onions, garlic, sun-dried tomatoes, and more mushroom (actually just the stems and gills from the mushroom caps). You could mix this recipe up a bit by using different sausages in place of the beef, and adding other ingredients with flavors that are unique enough to stand on their own and add interest to the stuffing – perhaps minced olives, or some fresh basil. Use your imagination!
- 6 large portobella mushrooms, about 6″ in diameter and with a nice deep cap (ours pictured aren’t quite what I would have liked, but they were what was available when I went to the store)
- 1 lb grass-fed ground beef (or use any variety of ground meat or sausage of your choice)
- 2 plum tomatoes, chopped fine
- 1/2 yellow onion, chopped fine
- 2 cloves garlic, peeled and pressed
- 8 oz fresh baby spinach (that’s about 16 cups of loose fresh leaves)
- 1/4 cup sun-dried tomatoes (not the oil-packed ones), sliced thinly
- 1/2 tsp sea salt
- 1/2 tsp black pepper
- 4 tbsp extra virgin olive oil
- a couple of tablespoons of almond meal (optional)
Preheat the oven to 350 degrees. Get a large sauce pan heating on medium-high heat, then toss in the spinach and cook – stirring constantly – until it has been wilted and reduced to a dark wet mass the size of your fist in the bottom of the pot. Turn off the heat and transfer the spinach to a mesh sieve or strainer and let drain and cool.
Get everything else cut up and into prep bowls (onion and garlic together, sun-dried tomatoes next to them, and tomatoes behind). Pop the stems out of the mushroom caps, then trim off the old dried end. Chop the stems up and transfer to a bowl. Using a spoon, carefully remove the “gills” from the inside of each mushroom cap – without damaging or tearing the cap itself – and transfer them to the bowl with the chopped stems. Finally, if your caps are not as deep as you’d like, or have a bit of a “hump” in the center where the stem had been attached, you can take a sharp knife and cut flat across to make the center a little deeper (as I did with these).
In the same saucepan you cooked the spinach, return it to the burner over medium heat. Pour in 2 tbsp of olive oil, then add the onion and garlic and cook for about 60 seconds. Add the ground meat and continue cooking until it is browned. While it is cooking, squeeze as much moisture as you can out of the spinach (work in golf-ball sized chunks to get a better squeeze on it), then transfer to the cutting board and chop it all up very well.
Depending on how fatty your ground meat is, you may want to drain it at this point. Then add in the mushrooms, tomatoes, sun-dried tomatoes, and spinach. Stir to mix well, then reduce heat to low and let heat to evaporate much of the moisture – about 3 to 5 minutes or so. When done, transfer to the strainer used for the spinach, placed over a bowl or pan, to allow to drain any remaining liquid.
Arrange the mushroom caps on a baking pan, top-side up, and brush with olive oil. Place in the oven and cook for about 3 to 5 minutes (you can do this while the stuffing mixture is heating above). Once you’ve put the stuffing into the strainer to drain, pull the mushroom caps from the oven and flip over so the open side is up.
Carefully spoon stuffing mixture into/onto the mushroom caps (how much is in versus on will depend on how deep the original caps were). Make sure to mound it up well above the cap. Since I had enough stuffing for six (or more) mushrooms, but was only able to buy four, I also grabbed a bell pepper out of the fridge and stuffed it too! Lightly sprinkle the tops with sea salt, black pepper, and then a little almond meal (looks a bit like parmesan to the untrained eye).
Pop them back into the oven for about 5 to 8 more minutes, until the mushrooms are tender and the almond meal on top starts to turn golden brown. Serve while warm, accompanied with a nice salad or simply all by themselves.