Which of the following is not a common espresso-based drink?

Chai tea is not a common espresso-based drink. Espresso-based drinks are typically made using espresso, which is a concentrated form of coffee brewed by forcing hot water through finely-ground coffee beans. Common espresso drinks include cappuccino, latte, and macchiato, all of which use espresso as a base along with frothed milk or steamed milk and other flavorings.

On the other hand, chai tea is a spiced tea made from black tea mixed with a variety of spices such as cardamom, ginger, and cinnamon, typically brewed with milk and sweetened. It does not contain espresso and therefore does not fit into the category of espresso-based beverages. This distinction is crucial for understanding the variety of drinks available at coffee shops like Starbucks.