Mince the garlic in a food processor. Add the chickpeas, lemon juice, 2 tablespoons water, salt, and pepper. Process until the mixture is almost smooth. With the machine running, gradually blend in the oil. Process until the mixture is completely smooth, scraping down the sides of the work bowl occasionally. Add the sun-dried tomatoes and dried herbs. Blend until the tomatoes and herbs are finely chopped. (The dip can be made 1 day ahead. Cover and refrigerate.) To serve, spoon 1 teaspoon of the dip on each crostini, and garnish with lemon zest or fresh herbs.