Soak the beans overnight in cold water to cover.
Drain the beans and transfer them to a large saucepan. Cover with 3 cups cold water, the coconut water and 2 teaspoons salt, set over medium heat and bring to a boil. Boil for 2 minutes, then turn the heat down to low, cover and cook until tender; depending upon the age of the beans, this will take between 30 and 45 minutes (older beans take longer).
When tender, add the coconut oil and lime juice and season with salt and pepper. Pour into a serving dish and garnish with the green onions.