Clean the bark, slice the ginger and boil with the cinnamon stick in 1 1/2 cups of water for 5 minutes; strain, cool and chill. Boil the brown sugar in 3 qts. of water; add mabi brew and stir to blend. Strain into a large pot; strain and ladle until foamy. Loosely top the pot or cap lightly in a bottle. Allow to ferment for several days. Store uncovered in the refrigerator until ready to use.