Clean calamari and slice into rings; 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 calamari in butter until the onions are translucent. Add the coconut milk, cooked luau leaves, salt and sugar. Simmer for 30 minutes.