I’ve used my sous vide machine to make steak and pork shoulder. In both cases, the meat goes in the bag with seasonings.

The pork shoulder cooks overnight at 175°F, and then the next day I dry thoroughly, then finish it in the oven for 15-20 minutes at 475°F to give it a crisp outer shell.

Steak only cooks for like an hour in the sous vide machine at 135°F, then dry and pan-fry to give it a crisp.

I’ve never cooked octopus, so I really don’t know how long it would take or what temperature. But my intuition is that the same basic process would work. Cook with seasonings in the bag by sous vide, then dry and pan fry to make a crispy outside.

Cooking longer in sous vide leads to more tender meat in the pork case. Longer leads to over cooking for steak. Don’t know what the effect of time is on octopus. There are probably people have experimented with it.