The success of this recipe depends on ripe, in-season tomatoes. A rasp-style grater makes quick work of turning the garlic into a paste.
1. Adjust oven rack to middle position and heat oven to 375 degrees. Using kitchen shears, cut around perimeter of each pita and separate into 2 thin rounds. Cut each round in half. Place pitas, smooth side down, on wire rack set in rimmed baking sheet. Brush 3 tablespoons oil over surface of pitas. (Pitas do not need to be uniformly coated. Oil will spread during baking.) Season with salt and pepper to taste. Bake until pitas are crisp and pale golden brown, 10 to 14 minutes. Set aside to cool. (Cooled pitas can be stored in zipper-lock bag for 24 hours.)
2. While pitas toast, whisk lemon juice, garlic, and 1/4 teaspoon salt together in small bowl. Let stand for 10 minutes.
3. Place tomatoes, cucumber, arugula, cilantro, mint, and scallions in large bowl. Break pitas into 1/2-inch pieces and place in bowl with vegetables. Add lemon-garlic mixture and remaining 1/4 cup oil and toss to coat. Season with salt and pepper to taste. Serve immediately.
