Grate the vegetables and squeeze out the moisture.
To make the Rösti, combine all the ingredients in a large bowl then mix well. Make sure you break up any clumps of flour (I find it best to use my hands for this).
Heat a little oil in a deep frying pan then fry spoonfuls of the mixture until golden brown and crisp on both sides and cooked through.
Remove from the pan and drain on kitchen paper. Repeat until all the mixture has been cooked.
To make the avocado cream, blend all the ingredients together in a food processor (alternatively just mash with a fork) and season to taste.