Blanch it, pull the skin off, lightly pound the mantle meat and pound the tentacles much heavier-------OR..... pressure cook the tentacles after removing the skin. Marinate in your favorite greek salad seasoning and enjoy. I have fond memories for having octopus salad for lunch in a seaside cafe outside of Naples . Slice thin rounds out of the tentacles works best too.
The only part I will feed to the butts is the end of the tentacles that are REALLY tough.