Preheat the oven to 180°C conventional (160°C fan-forced). Line a large baking tray with baking paper.
In a bowl, place the caster sugar, egg, lemon zest and olive oil. Mix well to combine.
0.75 cup caster sugar, 1 egg, 1 lemon, 0.5 cup extra virgin olive oil
Add the bicarb soda and flour and stir until just combined.
0.5 tsp bicarbonate of soda, 2 cups plain flour
Place the icing sugar in a small bowl. Roll the dough into small balls with your hands and dunk them in the icing sugar to coat. Lay them out on the baking tray.
2 tbsp icing sugar
Bake the cookies for 12–14 minutes. Remove and cool on a rack.