In a small mixing bowl, whisk together the Greek yogurt, mayonnaise, grated garlic, fresh chives, tarragon, lemon zest and juice, olive oil, salt, and black pepper until smooth and creamy.

Generously spread 2 tablespoons of your zesty yogurt-mayo sauce on one side of each slice of bread.

Layer half of the arugula, mozzarella slices, cucumber, and avocado on 2 of the bread slices. Top them off with a sprinkle of alfalfa sprouts.

Place the remaining two slices of bread on top, spread side down, and press gently to close the sandwiches.

Cut the sandwiches in half and serve immediately.