I was served this amazing soup in a Spanish tapas bar and loved the lemon grass flavour together with the octopus. The recipe below is a recreation of that dish.
Unfortunatly, when recreating this, I did not have my ISI Whipper nearby but if you have one, then just strain the soup, pour it into the canister, charge with 1 cream charger and discharge into the soup bowl. Add the octopus and chopped chili. Creating a foam of the soup gives another, very interesting, texture to this soup.

Serves 2 as a main course

½ medium sized potato
300 ml water
2 kaffir lime leaves, shredded
½ stalk of lemon grass, chopped
½ small chili, chopped, seeds removed
Salt and pepper
3 tbsp lime juice
100 ml whipping cream/double cream.
Red and/or green chili, finely chopped for decoration
200 g octopus, finely sliced or in bite size pieces

1. Boil the potato with the kaffir lime, chili and the lemon grass in the water.
2. Puree using an immersion blender.
3. Add the salt and pepper, lime juice and cream.
4. Heat and then whisk to create a bit of a foam.
5. Heat the octopus in the soup or in a separate pan (depending if it is pre-cooked or raw).
6. Place in serving bowls and decorate with the chopped chili.