Peel the cucumber and cut into half centimetre dice and set aside for serving.
Chop the dill finely and cut the capers and avocado into small cubes.
Slice the spring onion through the middle lengthways and finely slice.
Put the avocado in a mixing bowl with the lemon juice and stir to coat all the pieces.
Put the prawns, dill, capers and spring onions into the bowl with the avocado.Mix well.
Place a presentation ring in the middle of a plate and divide evenly.
Use a fork to press down so that the ingredients can stick together without gaps.
Refrigerate for an hour.
When you are ready to serve, gently remove the presentation ring and garnish with the king prawns ans cucumber cubes. Add a little extra dill for garnish.