Place the octopus in a heavy-based pot and slowly heat until the moisture starts coming out. Cover with a lid and steam on medium heat for about 1 hour.
Check occasionally and if the moisture evaporates, add 200ml of water and reduce the heat.
Make the dressing by combining all the ingredients. Set aside.
Heat the olive oil in a heavy-based pan over high heat. When the oil starts to smoke, toss in the onion, ginger, parsley and clams and stir. Once the onion becomes fragrant, add the wine and cover for 2 minutes.
Remove the lid and as each clam opens, remove it.
Remove and discard half of each clam shell, leaving the flesh in the remaining half shells.
Check the octopus is cooked by sliding a sharp point of a knife into the thick end of a tentacle. It should give a little but still be firm.
Remove the tentacles and slice them on an angle into thin slices.
Place the surf clams, sliced octopus and chopped garlic chives into a bowl and add 2 tablespoons of dressing per serve and a squeeze of lime juice. Mix well.
Mix 1 small handful of udon noodles into the clam and octopus mix and combine.
Serve by placing a pile of noodles in a bowl and arranging the octopus and clams throughout. Garnish with toasted sesame seeds and any leftover garlic chives.