Khao yum (rainbow rice salad) with nam budu dressing

Simmer red cabbage in water about five minutes; strain out the cabbage, keeping the purple water.

Add baking soda a smidge at a time until the water turns blue; check the colour on a plate. If it goes green, add a little acid to bring it back.

Cook the rice as normal in the blue water, in a stainless steel or non-stick pot, never aluminium, which reacts with the baking soda and turns the rice purple again.

Blitz shallots, garlic, the bottom of the lemongrass and ginger with a little water to a rough paste with no big chunks.

Put the paste on the stove; add fish sauce, a little shrimp paste, a lot of palm sugar, tamarind and two torn kaffir lime leaves.

Bring to a simmer for five to ten minutes until the herbs are cooked and the sugar dissolved; add water if it gets dry.

Taste for an equal balance of salty and sweet with barely any tartness; thin with water if far too strong, or wait and judge on the rice.

Toast desiccated coconut in a saute pan or the oven until dark brown and aromatic.

Tear pomelo into small pieces.

Blitz dried shrimp in a coffee grinder until shredded and fluffy, then toast quickly in a dry pan until it smells like barbecued shrimp.

Cool the dressing; it should run freely, thinned with water if thick.

Toss everything together at room temperature with a little dressing, adding lime juice to taste.