Pour 350ml water into a small saucepan with the sugar, soy sauce, garlic and ginger. Slowly bring to a simmer, stirring occasionally until the sugar has dissolved. Cook for 5 mins more or until glossy and slightly thickened. Combine the cornflour with 1 tbsp water and quickly whisk through the sauce. Whisk through the rice wine vinegar. If it’s still too thick, add a splash more water. Pour into a clean jar and leave to cool at room temperature.
Once cooled, will keep in the fridge for up to 1 week. Sprinkle with sesame seeds and spring onions just before serving, if you like.
