Cut off both ends of the cucumber, slice diagonally, and chop into small pieces. Thinly slice the onion and soak in water to remove bitterness, then drain.

Cut the boiled octopus into bite-sized pieces.

In a bowl, mix the dressing ingredients (sugar, salt, pepper, vinegar, olive oil). Add cucumber, onion, octopus, and chickpeas, then toss to combine.