Clean calamari and slice in rings, then set aside.
Wash luau leaves, remove stems and thick veins. In a pot, boil 3 cups of water with the Hawaiian salt and baking soda. Add the leaves to the boiling water and reduce heat. Simmer, partially covered for 1 hour. Drain, and squeeze out liquid.
Saute onions and cleaned calamari in the butter until the onions are translucent. Add the coconut milk, cooked luau leaves, salt, and sugar. Simmer for 30 minutes.