Powa Technologies has teamed up with UK supermarket chain Tesco to test a new mobile payment service.

Interested users can download the Powatag app (Android and iOS) and link their credit or debit card, choose the meal deal they want (sandwich, snack and drink), and then scan a QR code instore to checkout.

As often with payment services, the trial puts an emphasis on speed of transaction as a lure to shoppers and retailers.

“Take the 30 second challenge! Pick, pay and leave in 30 seconds. Monday 13th to Friday 17th October 2014,” according to Tesco’s marketing.

As a lure for guinea pigs to try out the service, the first 500 shoppers who signed up at a branch of Tesco in London’s Dean Street were treated to a free lunch.  After the freebies were gone, shoppers paid for their purchases.

Powa entered the payments market by offering a mobile point-of-sale service to retailers, then last summer the company acquired MPayMe and its QR code-based Znap technology so that it could also offer a payment service to shoppers.