In a blender or food processor, purée garbanzos and peanut sauce, scraping hummus mixture from container sides as needed.
Trim and discard zucchini ends. Cut zucchini lengthwise into 1/4-inch slices. Cut onion crosswise into 1/2-inch slices. Brush vegetables lightly with olive oil.
Place zucchini and onion slices on a barbecue grill over a solid bed of hot coals or high heat on a gas grill (you can hold your hand at grill level only 2 to 3 seconds); close lid on gas grill. Cook vegetables, turning to brown evenly, 10 to 12 minutes, transferring to a plate as cooked.
Spread cupped side of each pocket bread with 1/4 of the hummus and set on plates. Top each bread equally with zucchini, tomato, onion, and alfalfa sprouts. Eat with knife and fork.