Heat about 5mm of oil in a frypan til quite hot, then turn down to medium hot

Put onions into oil, stir and wait a bit.

Stir once every minute or two, not too often (this its a learned trick)

After 5 minutes or so, turn the heat down to medium. Then, after another minute or two, down to medium-low. Then low.

Drain oil, and put browned onions on a double thickness paper towel to cool.