If you have to have a certain taste for a lot of red wine vinegar (like me), you will love this as a quick snack. I've been eating this since I was a little kid. Apparently this was a pretty popular snack back in the old days, but I only know of it from my Grandma Greene.
1/2 cup of Red wine vinegar
3 Tbsp. of sugar
1 sliced up Tomato (of your favorite variety)
Mix the vinegar and sugar in a small bowl until the sugar starts to dissolve. Place the tomatoes into the bowl and enjoy.