The idea for this rendition of stuffed mushrooms actually came out of a need to create a fresh meal out of Thanksgiving leftovers. I had some lentils with caramelized onions and thyme, and a bowl of Brussels sprouts sautéed with truffle oil and parmesan cheese, but had no interest in serving them a second time in their original state. I wanted a comforting and hearty dinner for a cold night that still managed to be nutritious, so I roasted some portobellos until the excess water in the mushrooms had cooked out and soon I was left with a flavorful vehicle for the lentils and Brussels sprouts that made for an excellent vegetarian entrée. I was so pleased with how the dish turned out that I modified the recipe to make a version that did not require previously prepared ingredients, so that the meal could be enjoyed any night of the week.
This version, with lentils, baby spinach, an inexpensive drizzle of truffle oil (Trader Joe’s has done it again!) and a shower of grated parmesan, gets a finishing touch under the broiler until golden brown and piping hot. It’s a simple yet elegant meal to make that comes together quickly on a weeknight, and is packed with vegetables and tender lentils. These are not the typical stuffed mushrooms that are filled with cheese and breadcrumbs and served for holiday appetizers, but they’re just as delicious in their own way.
The next time you need a break from Christmas cookies and gift wrapping, throw a few portobellos in the oven and get ready to be pleasantly surprised.
Lentil Stuffed Portobello Mushrooms
4 Portobello mushrooms
2 teaspoons olive oil, divided
½ teaspoon sea salt, divided
½ onion, finely chopped
1 ½ cups cooked, seasoned lentils (see note)
3 oz. baby spinach, chopped
1 teaspoon chopped fresh thyme
½ cup water
2 teaspoons balsamic vinegar
1 ½ teaspoons truffle oil (if you don’t have truffle oil, you can substitute an equal amount of olive oil)
¼ cup grated parmesan cheese.
- Place a rimmed baking sheet on the upper rack of the oven. Then preheat the oven to 500F. While the oven preheats, remove the stems from the mushrooms, then carefully scrape out the gills with a spoon. Using a sharp knife, cut shallow crosshatches ½ inch apart on the back of the mushroom cap, creating a grid of shallow cuts—do not cut through the mushrooms. Rub the mushroom caps with 1 teaspoon olive oil and sprinkle with ¼ teaspoon sea salt. Once the oven has preheated, place the mushrooms, stem side down, on the hot baking sheet, then bake for 10 minutes, until the juices have begun to be released. With a metal spatula, carefully flip the mushrooms so that the stem side faces up, then roasted for another 10-12 minutes, until the liquid has evaporated.
- While the mushrooms roast, prepare the filling. Heat the remaining 1 teaspoon of olive oil in a non-stick skillet over medium heat, then add the onion and sauté until golden brown, 6-8 minutes. Add the remaining ¼ teaspoon sea salt, lentils, spinach, thyme, and water, and simmer for 3-4 minutes, until warmed through and the spinach has wilted. Add the balsamic vinegar and truffle oil, and toss to combine.
- Once the mushrooms are finished, remove them from the oven, and divide the lentil filling evenly among the 4 mushrooms. Top each mushroom with 1 tablespoon of the grated parmesan, then carefully return them to the oven for 4-5 minutes, until the cheese has melted and is beginning to turn golden brown. Serve immediately.
Note: I use the Trader Joe’s steamed green lentils in this recipe, and they are perfectly cooked and seasoned with salt. If you do not have access to those lentils, combine ¾ cup of green lentils in a saucepan with 2 ¼ cups of water and ½ teaspoon salt, bring to a boil, then simmer, covered, for 24-30 minutes, until the lentils are tender. Drain off any excess water before proceeding with the recipe.