Turn the urchin over so that the mouth is on top. Using kitchen shears, cut, remove, and discard the mouth. Invert the urchin to pour out the liquid into a waste bowl.
Flip the urchin back over and cut a larger hole with your kitchen shears and pour out any additional liquid or innards that remain inside.
Using a spoon, gently remove the uni roe one by one. Place each in a shallow bowl of salted water. Gently rinse the uni with the water in the bowl to remove any black pieces. You can also use tweezers to remove any black pieces. Place cleaned uni on a clean dish towel or paper towel.