Sweet and Sour Sesame Dressing

Process the onion in a liquidiser or food processor until smooth. Pass through a mesh sieve. Reserve 3 tablespoons of onion juice; discard the remaining pulp.

Combine the sugar, mustard powder and salt in the bowl of an electric mixer. Use the paddle attachment to mix the sugar until the spices are evenly blended. Pour in the reserved onion juice, soy sauce and rice vinegar. Mix for several minutes until the sugar has begun to dissolve. Slowly drizzle in the rapeseed oil with the mixer running at a medium-high speed. Add the toasted sesame seeds and continue mixing 1 minute more.