As the Polenta and the Octopus take a similar amount of time we can start with the boiling of the octopus, then set it for a half hour while making the polenta. In a large saucepan, fill about 3/4 the way with water and add a few tbsp of salt. Bring up to a boil. When boiling, reduce to a simmer and drop in the octopus tentacles. Set on a back burner for at least a half hour.
In a pot begin boiling the 300 ml of water with a pinch of salt. When you reach a rolling boil, slowly pour in the cornmeal while whisking rapidly to prevent any clumps. Lower the heat to medium and continue whisking for 5 minutes straight. By now the there should be about an equal amount of cornmeal to water so it's like a thick slurry. Put the heat on very low and lid the pot. You will stir it up every 5 minutes for the next 25 minutes.
As you have a bit of free time since all you need to do is stir the polenta every 5 minutes, let's make the avocado cream for the salad. Using a stick blender (or just a regular blender), mix together one whole avocado with the heavy cream and a pinch of salt until you're left with a light green cream. Chop up 1 tomato as well, and peel the skin off 10 or so chickpeas.
When the polenta is done and thick, drop in the butter and mix once more. When the butter is fully incorporated, add the grated parmesan cheese. Mix thoroughly and set aside for 10-15 minutes off the flame with the lid on.
Take the octopus tentacles and drop them in a bowl of ice water. Empty the saucepan. Dry the tentacles with a towel and rub down with the balsamic glassa.
In a very hot grill pan or skillet add the olive oil and the chopped shallot, then drop the balsamic octopus tentacles down and cook for just a minute or so per side. As we are using a high flame with low smoke point oils, the balsamic may flame up so best to be careful when doing this step. This is okay however and will make a nice glaze/crust caramelize along the edge of the octopus' tentacles.
Plate the dish. Smear the avocado cream down and top with the chopped tomatoes and some chickpeas. Add a dollop of polenta and form into an oval or circle, then top with the balsamic grilled octopus. Salt the salad to taste and serve.