California Avocado Flat Bread Sandwich Recipe - Delicious & Easy!

Ingredients

• 0.75 cup white wine vinegar , divided
• 0.5 tbsp finely chopped fresh garlic
• 0.5 tsp salt
• 0.5 tsp freshly ground black pepper
• 1 cup olive oil
• 2 cup chopped sweet onion
• 2 cup chopped sun-dried tomato
• 24 rounds flat bread , such as pita - about 7 inches in diameter
• hearts of romaine leaves - as needed
• 3 cup romano cheese , grated
• 12 california avocados