Boiling / Pressure cooking:
Drain, then add this arbi to a pressure cooker, fill water as much that Arbi is submerged in water. Cook on full flame till one whistle. Then simmer and cook until 1 more whistle. Shut the flame and let the steam release on its own.
Once the steam is released, peel the skin and keep the arbi pieces aside.
If you choose to boil them in a pan instead, then boil them in water until soft inside and then drain. Either way, it does not take too long. But pressure cooking reduces time to cooking within 30 min.