Portobello and Havarti Burgers with Caramelized Onions

Ingredients:

• 2 tbsp olive oil divided
• 1 onion sliced thinly, sweet yellow
• sea salt to taste, fresh cracked pepper
• black pepper to taste, fresh cracked pepper
• 4 portobello mushrooms stems removed and cleaned, large
• 4 lices havarti cheese

Mushroom Marinade:

• ¼ cup balsamic vinegar
• 1 tbsp olive oil
• 1 tbsp basil chopped finely, fresh leaves
• 1 clove garlic minced
• sea salt to taste, fresh cracked pepper
• black pepper to taste, fresh cracked pepper

Roasted Garlic Mayonnaise:

• 1 garlic see recipe here, roasted bulb
• 2 tbsp mayonnaise
• sea salt to taste, fresh cracked pepper
• black pepper to taste, fresh cracked pepper

Serving:

• 4 Hamburger Bun toasted
• tomato slices
• basil fresh leaves