Grilling intensifies the flavor of the marinated portobello mushrooms in this recipe. Topped with goat cheese, these sandwiches are great for lunch or dinner.
Hold a mushroom, cut side up, in your hand. Using small sharp knife, carefully scrape to remove most of dark brown “gills.” Repeat with remaining mushrooms.
Prepare marinade in large, shallow glass dish. Add mushrooms and turn to coat. Let mushrooms marinate at least 30 minutes or up to 4 hours.
In medium bowl, whisk together vinegar, oil and mustard to make dressing. Season with salt and pepper and set aside.
Prepare hot charcoal fire or preheat gas grill on high. Grill mushrooms, turning often, until tender and grill-marked, about 10 minutes. Lightly toast rolls, if desired.
To assemble sandwiches, spread goat cheese on both sides of rolls. Arrange mushrooms on bottom of each roll. Add arugula to dressing in bowl and toss well. Place arugula leaves on top of each mushroom, cover with bun tops and serve.