Heat the grapeseed oil in a saucepan to 70°C (155°F). Add the sliced ginger and spring onion and heat for 10 minutes, maintaining the oil at 70°C (155°F). Remove the pan from the heat and allow to infuse for 2 hours. Strain the oil through a sieve lined with muslin cloth, discarding the ginger and spring onion. Put the infused grapeseed oil aside until needed. Makes