In food processor fitted with chopping blade, combine chickpeas, dried tomato halves, water, lemon juice, 1 tablespoon olive oil, the garlic, and 1/2 teaspoon salt. Process until chickpea mixture, or hummus, forms a smooth puree. Set aside. Cut cucumber lengthwise in half and seed. Finely chop cucumber halves and place in small bowl with shredded carrot and radishes. Stir in remaining tablespoon olive oil, the vinegar, black pepper, sugar, and remaining 1/8 teaspoon salt. To assemble sandwiches, cut each pita in half to make two pockets. Spread about 2 tablespoons hummus in each pocket and top with one lettuce leaf. Spoon cucumber mixture into pockets so that it is separated from the hummus by lettuce (this will help prevent the hummus from becoming soggy). Serve immediately. Nutritional information per sandwich-protein: 12 grams, fat 10 grams, carbs: 55 gram; fiber: 7 grams; sodium: 713 milligrams; cholesterol: 0; calories: 355.