Place the macadamias and water in a high-speed blender and blend for 2-3 minutes until thoroughly combined.
Add the mustard, lemon juice and salt and blend to combine. With the motor running, add the oil in a thin, steady stream until the mixture thickens. Initially it won’t be as thick as a traditional mayonnaise, but will thicken further with refrigeration.
Season to taste with extra lemon juice and salt if desired.
Serve with sweet potato chips, sprinkled with coriander and chilli flakes.