Well, it really depend on how big is the budget of the restaurant and also depends on how unique is your work.
Do u have to "sell" your work? Or do they come for you because it is something that you have that they want?
You can charge whatever you can but they might buy it.
Normally, I would charge by the hour and release per image type of agreement. That way, you just need to make sure you get the best images and clients pays for what they want at the same time, you don't spend whole day to wait for the clients to get their act together.
But of course, you just need to put number to your hourly rate as well as rate of release per image basis.
Hope it helps.
Regards,
Hart