Place the green beans and zucchini in a large pot and lightly steam (for 10-15 minutes) or boil (for 5-7 minutes) until tender but still somewhat firm. Remove from heat, strain and rinse the vegetables with ice cold water, then set aside.
Meanwhile, make the dressing by combining all of the ingredients in a food processor and blending until the herbs are finely chopped.
In a large bowl, combine the drained chickpeas, corn, tomatoes and green onion. Add the blanched green beans and zucchini, then pour the dressing on top. Stir together until everything is well-coated. Serve immediately or store in an airtight container in the refrigerator for up to 2 days.