Poke holes in the top of the tomatoes with a skewer.
In a saucepan, heat the vinegar, salt, sugar and 1 cup water to a rolling boil.
In a mason jar, add the rosemary, lemon zest, peppercorns and garlic. Add the cherry tomatoes and pour over the hot vinegar mixture. Screw a top on the mason jar. Let cool, then refrigerate. The pickles will last up to 2 weeks refrigerated.