Portabella Burgers with Roasted Red Peppers and Pesto

• ¼ c balsamic vinegar
• ¼ c extra virgin olive oil
• 3 garlic cloves, minced
• 1 tsp kosher salt
• ¼ tsp crushed red pepper
• 4 portabella mushroom caps
• 2 tbsp pesto
• 2 tbsp mayonnaise
• 1 red bell pepper, halved and seeded
• Nonstick cooking spray
• Sprouts or watercress
• 4 brioche buns

Combine first 5 ingredients in a large zip-top plastic bag; add mushrooms. Seal and marinate at room temperature for 2 hours, turning bag occasionally. Remove mushrooms from bag; discard marinade.

In a small bowl, combine pesto and mayonnaise. Cover and refrigerate until ready to use.

Prepare grill to medium heat.

Place pepper halves on grill rack coated with cooking spray; grill 15 minutes or until blackened, turning occasionally. Remove from grill, let cool and slice into strips.

Place mushrooms, gill-sides down, on grill rack coated with cooking spray; grill 4 minutes on each side. Place buns, cut-sides down, on grill rack coated with cooking spray; grill 30 seconds on each side or until toasted.

Spread 1 tbsp pesto mayo on bottom half of each bun followed by mushroom cap, a few slices of bell pepper and a heavy pinch of sprouts. Cover with top halves of buns and serve.