Prepare the dressing by combining the apple cider vinegar, lemon juice, olive oil, allspice in a small bowl. Season with salt and pepper to taste. Set the dressing aside.
In a medium saucepan, heat the 2 teaspoons olive oil over medium high heat. Add the couscous, toss, and toast for about 1 minute or until couscous is coated with the oil and starts to turn golden.
Add the water and salt to the pan. Bring the mixture to a boil, cover, and reduce the heat to medium-low. Cook for 8-10 minutes or until the Israeli couscous is tender. Drain the cousous in a colander and rinse with cold water.
Put the couscous in a bowl and pour the dressing over. Refrigerate until cool.
While the couscous is cooling, combine the sliced tomatoes, cucumbers, and scallions in a mixing bowl.
Add the cooled, seasoned couscous to the vegetables. Toss well to combine. Refrigerate for up to 30 minutes or serve immediately.