Place the potatoes in a medium pot with the water, vinegar, and salt. Bring to a boil, and simmer until they are tender. (The vinegar adds flavor as well as helps the potatoes to keep their shape even after they are tender.) When the potatoes are tender, drain and allow to cool for 10 minutes. Meanwhile, in a medium bowl combine the tomatoes, onions, mustard, thyme, garlic, olive oil, vinegar, salt, and pepper. Mix well. Pour into a zip lock baggie. Place the still warm potatoes into the bag and coat. Allow the potatoes to sit until they are room temperature, seal the bag and into the cooler they go. The potatoes will absorb more flavor if they are still warm when added to the marinade.
Yield: 6 servings