Put the frozen octopus in a pan. Add one bay leaf and one of the onions, peeled.
Let it cook with the lid on and in low heat until the onion is tender. When the octopus is almost ready, peel and chop the other onion and crush the garlic cloves with your hand.
Melt the butter in a pan, add the crushed garlic cloves and, they start to brown, add the chopped onion and cook until tender. Add the risotto rice and let it fry, mixing always with a wooden spoon until it looks translucent. Pour the red wine and simmer, stirring constantly until the rice absorbs the liquid completely.
Drain the octopus and add it to the liquid when the water starts to boil. Season with salt and pepper and keep adding of ladle-full of the hot stock the octopus to the risotto, one at a time, stirring each time until the liquid is absorbed.
Season the octopus with salt and pepper and cut it into small sections. When the rice no longer has a chalky core, put the octopus pieces and aromatize generously with chopped coriander.