Blue Cheese Portobello Burgers

Blue cheese and slow-cooked onions turn a grilled portobello into an indulgent portobello burger. Ruby port—a sweet fortified wine—gives extra depth of flavor to the caramelized onions.

• Total time: 1 hour

Ingredients

• 3 tablespoons extra-virgin olive oil, divided
• 1 tablespoon balsamic vinegar
• 3 cloves garlic, minced
• 4 large portobello mushrooms, stems removed
• 3 cups thinly sliced red onion
• 2 tablespoons water
• ¼ cup ruby port
• ½ teaspoon salt, divided
• ¼ teaspoon freshly ground pepper, divided
• ½ cup crumbled reduced-fat blue cheese (2 ounces)
• 4 whole-wheat hamburger buns
• 1 cup baby arugula
• 4 thick slices tomato

Directions

1. Whisk 2 tablespoons oil, vinegar and garlic in a bowl. Brush the mixture all over mushrooms and let stand for 30 minutes.
2. Meanwhile, heat the remaining 1 tablespoon oil in a large skillet over high heat. Add onion and cook, stirring frequently, until beginning to brown, about 5 minutes. Reduce heat to low, add water and cook, stirring frequently, until the onion is browned and very soft, about 15 minutes.
3. Add port; cook, stirring occasionally, until mostly evaporated, about 3 minutes more. Stir in ¼ teaspoon salt and ⅛ teaspoon pepper. Remove from the heat and cover.
4. Preheat grill to medium.
5. Sprinkle the mushrooms with the remaining ¼ teaspoon salt and ⅛ teaspoon pepper. Grill, gill-side down, for 5 minutes. Turn over and top each with 2 tablespoons cheese. Grill until the mushrooms are tender, 4 to 5 minutes more.
6. Toast buns. Divide the onions among the mushrooms. Serve (cheese-side up) on buns with arugula and tomato.