Boil the octopus for 45-50 in a pot that can cover the octopus with water and you can put a lid on. To have a tender octopus leave it cool down in its own water for 30min without the lid. Do not take it out right after boiling because it will become gummy.
Peal the potatoes and cut them in shapes you like put them in a baking tray, add 2table spoon of olive oil and mix to coat them. Season them with salt&pepper and put them in the oven for 35-40 min @ 180C.
Once the octopus cooled down, take it out and remove the head leaving only the tentacles, dive it in half 4/4 tentacles and start cutting them one by one. Dry them on paper to remove the eater and put them in a tray. Add on top of them olive oil (will make them crispy) and season with salt and pepper. Roast them on a high heated pan 3-4 at the time (do not crowd the pan) 2 min each side. Remove and let it rest for 5 min.
Add 2/3 octopus tentacles with potatoes on a plate drizzle some olive oil on the octopus and fresh lime.