These portabella mushrooms are marinated in a homemade barbecue spice mix and grilled until tender. When served, they are loaded up with sweet grilled red onions and savory garlic and chive mayonnaise.
2 teaspoons chili powder
1 teaspoon dark or light brown sugar
1 teaspoon fine sea salt
1 teaspoon garlic powder
1 teaspoon onion powder
1 teaspoon smoked paprika
½ teaspoon ground black pepper
1/3 cup extra virgin olive oil
4 portabella mushrooms, stems and gills removed
1/3 cup mayonnaise
1 teaspoon chopped chives
¼ teaspoon garlic powder
¼ teaspoon fine sea salt
1 small red onion, sliced (keep rings intact)
4 lettuce leaves
Olive oil for grilling
Mix all marinade ingredients in a small bowl. Place mushrooms on a baking sheet. Drizzle marinade over mushrooms and rub liberally to coat all sides. Let sit for 15 minutes.
Preheat grill to high heat.
To make garlic mayo, stir together mayonnaise, chives, garlic powder and salt in a small bowl. Refrigerate until ready to serve.
Brush grill grate with olive oil. Place mushrooms and onion rings on grill. Cook for 5 to 7 minutes on each side, until both are darkened and tender.
To serve, spread bottom of each bun with mayonnaise, top with lettuce and a few onion rings. Add mushroom and cover with top bun.