To make pickling liquid, heat the coriander and mustard seeds in a small frying pan over a medium to high heat for 2 minutes, or until fragrant. Transfer to a plate.
Combine vinegar, sugar and salt in a small saucepan. Stir over a medium heat until sugar is dissolved. Bring to boil. Transfer to a medium heatproof jug. Stir in seeds and chilli flakes. Set aside to cool.
Cut Qukes® in half lengthways. Divide between two sterilised jars (500ml capacity). Add 1 tablespoon dill to each jar. Pour over cooled pickling liquid. Seal tightly with lid. Refrigerate for a minimum of 4 hours. Pickled Qukes® are best eaten within 3 days.