The recipe for hummus at Israel's Abu Hassan restaurant has been a secret since the 1950s, but its presentation is a spectacle. A server with a big spoon scoops chickpea puree onto a plate, then spins the spoon and plate in opposite directions to spread it. A drizzle of olive oil and healthy sprinkle of lemony-tart sumac powder completes it. Visit our blog to learn more about sumac and see sumac substitutes.