Drain the cans of tomatoes well; reserve 1/4 cup of the liquid for use in the dressing.
In a medium mixing bowl, stir together the well-drained tomatoes, cucumbers, scallions, mint, ¼ teaspoon of the salt, and the pepper.
In a jar or sealed container, shake together the lemon juice, olive oil, tahini, garlic, cumin, the remaining 1/8 teaspoon salt, and 2½ tablespoons of the reserved liquid from the can of tomatoes. (Note: If desire a thinner dressing, add more of the reserved liquid.)
When ready to serve, drain the tomato-cucumber salad of excess liquid and transfer to a serving bowl or individual bowls. Drizzle the tomato-cucumber salad with the lemony-tahini dressing, sprinkle with the pine nuts, if using, and additional fresh mint leaves, and serve.
