In effect, you tell the bot what you want by saying "Alexa, order sushi from Amazon Restaurants." It'll pull up your history and suggest restaurants or cuisine types, then list meals that you've ordered before. After you pick one, it'll place the order and have it sent to your default address. Amazon was likely forced to do it that way to avoid making the process overly complicated, given that takeout orders are hard even for a human.

The service is available in a limited number of US cities, including Manhattan, Dallas, Chicago, Los Angeles and Seattle. (There's no word on it coming to the UK yet.) If you're in one of those cities, it should be easy to place an order -- Alexa is in so many devices now that you might even have the service without knowing it.