Ask your fishmonger to clean the octopus so that at home you only need to give it a good rinse under fresh water. I suggest you check “octopus preparation”, featured in the top tips section of the website, where you can find some good tips on how to clean an octopus and how to tenderise its meat.
When the octopus is ready for cooking, put it into a large pan.
Add the carrot, the celery and the half onion to the pan and then pour the wine over.
Fill the pan with water to cover.
Put the pan onto the cooker and boil until the octopus is tender. A rough guide is to boil for 1 hour for each kilogram of octopus, but this generally applies only if you have properly tenderised the octopus meat before boiling.
Do not forget to season the water with salt before the boiling starts (just a couple of pinches).
Halfway through the boiling time you can turn the octopus over and continue boiling. When you think it is time to remove the octopus from the pan, try to cut one of the tentacles with a knife. If the tentacle is tender and easy to cut, then turn the cooker off and let the octopus cool down enough to handle it.
During the boiling, the octopus skin will turn to a purple colour. Remove the main loose bits with your hands, in order to uncover most of the white meat.
Now, the octopus is ready for the final stages.
While the octopus is boiling, peel the potatoes.
Put the potatoes into a pan and boil them for about 15-20 minutes or until they are tender. You can use the microwave if you prefer; this way the potatoes will contain less water.
When the potatoes are ready, slice them.
Chop the parsley.
Now, that everything is ready, chop the octopus into pieces. You can cut the tentacles into small discs.
Add the sliced potatoes.
Add the chopped parsley.
Use a generous sprinkling of extra virgin olive oil. Some people also like to add a few drops of vinegar, but this is to your personal taste.
Finally, season with salt and serve it.