If you want to eat Okinawan local food, let's go to the Bento shop. You can find it anywhere in Okinawa. The shop sells Okinawan and Japanese general food Bento.
The most advantage is the Bento is Okinawan REAL daily food for workers and students. It is not an Okinawan special food restaurant that is for only touristic visitors, it's real food for Okinawans. And the price of Bento, you should be surprised about it. The price is only 300 to 500 JPY (around 2.5 to 4.0 USD), quality and price are the best of food in Okinawa.
How to find a Bento shop?
You can find in the map app, and also the signboard "OBENTO" on the roadside shop. Generally, the shop is really local and old fashion, so it seems to reject one-time touristic visitors, but it isn't, they are welcome to everybody including the visitors.
How to pay Bento shop?
Bento shops accept only cash in general. So prepare some Japanese cash in your pocket, 1000 JPY is enough for Bento.
Where do you eat the Bento?
Bento shop doesn't have eat in spaces, so you eat Bento at a beach, a park or in the car. Ofcorse the best place is beach for eating. You can feel Okinawan sea wind and wave, and then Bento taste becomes maximum value.