How to Make It
In a large pot, combine the onion, carrot, celery and water. Add a small handful of salt and bring to a boil. Add the octopus and simmer over moderate heat until tender, about 45 minutes. Let the octopus cool in the broth for 30 minutes, then drain.
Meanwhile, put the potatoes in a large saucepan, cover with cold water and boil until tender, about 30 minutes. Drain and let cool slightly. Peel the potatoes and cut them into 3/4-inch pieces.
In a medium bowl, toss the potatoes with 3 tablespoons of the parsley and 3 tablespoons of the olive oil; season with salt and pepper.
4.Cut the octopus into 3/4-inch pieces and transfer to a bowl. Add the remaining 3 tablespoons of parsley, 3 tablespoons of olive oil and the garlic and jalapeño. Season with salt and pepper and toss well. Transfer the potatoes and octopus to a large platter and serve warm or at room temperature.