Dragon fruit. Origin: Vietnam
This fruit contains a lot of water and minerals and other different nutritional ingredients. It is lightly sweet and it's good for the liver, and works also as a laxative, providing fiber which is very suitable for the diet (according to popular experience, an obese person who eats dragon fruit regularly can reduce his/her weight naturally). It is also good for people with a high blood pressure and diabetes.
In Portugal it is too expensive to be eaten regularly.