When it starts to boil, add the whole onion (cleaned and washed), the bay leaf, make the fire as small as possible, cover with a lid (leave a crack to let the steam out) and let it boil. If you make commercial chicken, leave it for 1-2 hours, if it is made from pork / beef legs, it should boil for 4-5 hours.
Careful! It should boil very slowly, you can barely see the air bubbles.