Clean and section the octopus (or get your fishmonger to do it for you) and wash it well
Place the octopus into a pan with the bay leaf and onion. Cover with water and bring to a simmer. Simmer for around 45 minutes until tender. Check this by inserting a fork or toothpick into the thickest part of the flesh. If its tender and soft it's cooked to perfection.
Meanwhile make the dressing: mix together the olive oil, lemon juice, chillies, salt and pepper
Once cooked, let the octopus cool in the liquor. When cool drain and reserve the onion from the water. Slice the octopus into 1cm pieces.
Toss the octopus and onion with the dressing and serve