If you're using dry ukwa, soak it overnight in plenty of cold water. If using fresh ukwa, skip this step.
*Wash the dry fish with hot water and salt and break into pieces.
*Wash the ukwa thoroughly in cold water. Use a sieve for this process to get rid of any sand.
*Pound the pepper.

Put your ukwa in a pot and add boiling water (the water should be about 1-2inches above the ukwa). Add your dry fish and some salt; cover the pot and cook till the ukwa is done.
Note: Salt acts as a tenderizer so you won't need potash if you use this method.