Pre-heat oven to 150°C. Grease two oven trays.
Beat butter, rind, and sugar in a large bowl with an electric mixer until light and fluffy.
Stir in flour in two batches.
Knead dough lightly on a floured surface until smooth.
Divide dough in half; shape each, into approx. 20cm rounds. Mark each round into six (or 12) wedges; prick with a fork. Pinch edges of rounds with fingers; sprinkle with white sugar.
Bake shortbread approx. 40 mins. Stand 5 mins; using a sharp knife, cut shortbread into wedges. Cool on trays.
Top tip:
We used White Wings® Gluten Free Plain Flour