Step 1

Preheat the oven to 400 degrees Fahrenheit and line a rimmed baking sheet with parchment paper. Set it aside.

Step 2

Prepare the mushrooms for roasting: Fill a small bowl with water. Wet a kitchen sponge (or a sheet of paper towel) in the bowl and squeeze out any excess water. Gently wipe the large mushroom caps to remove any dirt and debris.

Step 3

Remove the gills and the stem: Turn the mushrooms upside down and place one in the palm of your hand. Using a paring knife, slice off the mushroom’s inner edges while slowly rotating its cap. Then, use a small spoon to gently scrape the mushroom’s gills. Be careful not to dig too deep into the flesh of the mushroom. Continue working around the mushroom until you remove all of the gills. Remove the stem by gently twisting it from the bottom. Continue with the remaining mushrooms.

Step 4

Brush with oil and season: Place the portobello mushrooms on the parchment-lined sheet. Lightly brush each mushroom with approximately ½ teaspoon olive oil and season them with ¼ teaspoon salt and a pinch of pepper on both sides. If you do not have a brush, you can also use a vegetable oil cooking spray to lightly coat them with oil.

Step 5

Roast in the oven: Arrange the mushrooms on the baking sheet with the gills side facing down. Bake them in the oven for 10 minutes, flip them, and then bake them for another 5-7 minutes.

Step 6

Serve while they are still warm.