Seems like it would be hard for a competitor to gain a foothold. But it might be possible: Contact all the restaurants in a given area. Propose them a service

Seems like it would be hard for a competitor to gain a foothold. But it might be possible: Contact all the restaurants in a given area. Propose them a service similar to OpenTable. Guarantee to them a lower price and greater control. Market yourself as restaurant owner friendly. Launch the service and advertise in the selected area to reduce costs.