Grilled Portabello Burgers

• 1/4 C. olive oil
• 2 T. balsamic vinegar
• 4 portabello mushroom caps (trim stems even with the caps)
• 2 red peppers, seeded and halved lengthwise
• 4 round slices sweet onion, about 1/8 in. thick
• 1/3 C. crumbled feta cheese
• 4 hamburger rolls, split

• Heat grill on medium.
• Combine oil and vinegar in a small bowl; brush both sides of the peppers. Spoon remaining marinade over mushroom gills (underside of mushrooms).
• Grill peppers until tender and lightly charred on both sides; remove from grill.
• Turn heat to high. Grill mushrooms, gill side up, 3 to 4 minutes. They should be hot throughout yet still firm enough to hold their shape.
• Place mushrooms, gill side up, on the bottom half of each roll. Top with cheese, onion, pepper and top half of the roll.