Place the tomatoes in a mini food processor and pulse until minced but not pureed. Scrape into a bowl and stir in the olive oil and the vinegar.
Place the garlic, cumin, and salt in a mortar and, using a pestle, mash them into a paste. Add 3 to 4 tablespoons cold water and stir into the tomato mixture. Add the mint and taste for seasoning, adding salt to taste.