Pierce each tomato 3 times using a wooden pick or skewer, and place tomatoes in a large glass bowl. Bring vinegar, next 4 ingredients and, if desired, ginger, and 1 1/2 cups water to a boil in a large saucepan over high heat. Remove from heat, and pour over tomatoes. Cool 1 hour. Cover and chill 24 hours before serving. Refrigerate in an airtight container up to 2 weeks.