- Put the sugar, lemon and lime zest and juice in a heavy-based saucepan. Slowly bring to the boil, stirring to dissolve the sugar.
- Once the sugar has melted, add the cream and stir well. Gradually bring to the boil. As soon as it starts to bubble, remove the pan from the heat, pour in the milk and stir.
- Halve the avocados, then remove the stones, scoop out the flesh and place in a food processor or blender. Pour in the milk and cream mixture and blitz until smooth, scraping the sides to make sure there are no chunks of avocado left.
- Pour the mixture into a shallow plastic container and place in the freezer. Take it out after a couple of hours and whisk it by hand or with an electric whisk. Repeat the process twice, then return the avocado ice cream to the freezer for a final freeze.
Find more fabulous recipes in Carnival! by David Ponte, Lizzy Barber and Jamie Barber (Quadrille £10).