Cut a small x in skin of blossom end of each tomato. Blanch tomatoes in a saucepan of boiling water 3 seconda and immediately transfer with slotted spoon to bowl of ice water to stop cooking.

Drain and peel, transferring to large, shallow dish.

Stir together vodka, vinegar, sugar, and zest until sugar is dissolved, then pour over tomatoes, gently tossing to coat.

Marinate, covered and chilled, 30 minutes to 1 hour.