Squeeze or scoop the avocado from the skin into a small bowl. Mash with a fork and stir in the vinegar, oregano, yogurt and garlic to make a smooth spread. Thinly spread the avocado mixture onto one side of each slice of bread.
Top 4 of the slices of bread with the arugula, tofu, onions and sun-dried tomatoes. Place 4 of the remaining slices on top, avocado-side down. Top with the cucumbers, pepperoncini, provolone and roasted peppers. Place the remaining bread slices on top, avocado-side down.
Insert bamboo picks into each sandwich, cut in half on the diagonal with a bread knife and serve.