Step by step

1. Slice the grapefruits in half. Place the Citrus Press Blender accessory on the K400 blender. Turn to speed 1 and extract the juice from the grapefruits. Measure out 380 ml of the fresh juice and pour into an ice cube tray. Place in the freezer for 4-6 hours until frozen. Keep the remaining grapefruit juice.

2. Slice the limes and extract the juice on speed 1 using the Citrus Press Blender accessory. Add the fresh lime juice into the jug of the K400 blender.

3. Add 60 ml of the grapefruit juice.

4. Add sugar, maple syrup and frozen grapefruit juice.

5. Choose the Icy Drink setting and press the on button. Let the cycle run. If needed, repeat the Icy Drink setting programme until all ingredients are blended together.

6. Place the lime sugar in a shallow bowl. Use a wedge of fresh lime juice and run it around the rim of the glasses to moisten it. Dip the glasses in the lime sugar.

7. Divide the frozen mocktail between the glasses and serve immediately.

8. To make lime sugar, mix 50g course sugar with zest of 1 lime and place on a baking tray with parchment paper. Let it sit for 1 hour to dry and keep refrigerated in an airtight container.