Place macadamias in a ceramic or glass bowl or jug and cover generously with water – about 2 cups but no need to measure.
Soak nuts for at least 6 hours (and less than 48).
Drain, discarding soaking water. Place nuts in a food processor. Add lemon juice, a good pinch of sea salt flakes and 1/2 cup water and process until as smooth as you can get it. Scraping down the sides a few times.