Thaw the frozen octopus and cut it into bite-sized pieces.
Thinly slice the red onion, sprinkle with salt and soak in water. Once the spiciness is gone, wipe off the moisture.
Slice the yellow bell pepper thinly.
Blanch the cherry tomato, peel it, remove the seeds, and cut it into bite-sized pieces.
Cut the chives into 5cm (2.0in) lengths.
Finely chop the shiso leaves.
Mix the marinade/dressing ingredients in a bowl then add the octopus, red onion, bell pepper, and tomato. Toss lightly to combine, then chill in the refrigerator.
Add chives to bowl of marinade/dressing, mix well, and serve in a bowl. Sprinkle with green perilla and drizzle with olive oil.
