According to Happy Cow the choice of vegetarian restaurants on Okinawa is rather limited. And since we were all the way in the North, the Jai Thai restaurant in the city of Chantan was the shortest drive. And... Jai Thai restaurant is easy to find! It is located near the main road in so-called "American Village".
The menu has two full pages of vegetarian (many vegan) meals which all looked delicious. However, that's where the good news ends. As the name implies, many soldiers from the nearby American army base frequent "American Village". They are very loud and completely ignorant of Japanese customs. Do not expect a quiet or relaxed atmosphere here, the Americans shout at each other rather than talk to each other.
Also, the portions served are American sized. When we saw HUGE the portions which were being served to the Americans, so we decided to order one plate and share it amongst two persons. And still we couldn't finish everything!
As a starter we ordered a tofu with nuts and spicy lemon dressing on a bed of cabbage which I liked, but my friend disliked. The main menu was tofu and noodles, which we both disliked. It was oily and rather tasteless.
When we left the restaurant to explore American Village, we found a true vegetarian restaurant ("Tamie's Kitchen") just a few doors away. It turns out Okinawa offers many vegetarian choices, you just have to look a bit harder than usual.
Cons: fat, oily food, loud, rude Americans