Combine the chicken breasts, vinegar, olive oil, and garlic. Season with salt and pepper. Marinate for at least 4 hours or overnight.
Preheat the grill.
Remove the chicken from the marinade. Place the chicken on the grill and grill for 4 minutes per side, or until the juices run clear. Remove the chicken from the grill and set aside.
In a food processor, combine the sundried tomatoes, goat cheese, sour cream, oregano, basil and thyme. Process until well blended. Season the cheese mixture with salt and pepper. Set aside.
Slice each chicken breast half in half. You should have 18 pieces that are each approximately 2 ounces. Cut focaccia into 18 (3-inch by 3-inch)squares. Cut each square in half horizontally. Spread the sundried tomato goat cheese spread on the bottom half of each piece of focaccia. Top the spread with a piece of chicken. Place the top piece of bread on top of the chicken. Serve at room temperature.
From Food Network Kitchens