You've got to tenderize it. Smash it again the pavement when you get to shore for starters, then, boil the sh$t of it. Not sure how long my wife does it for, but, its at least 20 minutes plus depending on size. It isn't tough to chew if prepped right. I've never heard of the milk thing. Once we boil it, let it cool cut up into small pieces and make some cerviche and serve in a great salad or pulpo Vizcayo. Small is always better.