Heat olive oil over high heat. Carefully toss in fresh thyme and saute for about one minute, being careful as the oil will pop. Fold in tomatoes and sear for a few minutes until skin is slightly blistered. Add in garlic and remove pan from heat. Season with salt and pepper. Add in vinegar. Place in a bowl and refrigerate until cool. When cool, add in mozzarella balls and fresh basil. Toss gently and serve on crostini rounds