In a large saucepan with a lid, melt the butter and gently fry the vegetables and garlic without colouring them, stirring frequently.
When continuing the process, it took longer before the distilled water solution turned bright red-pink after stirring and the colour of the solution got darker.
In a separate pan, melt the butter, add the flour, and cook on a low heat, stirring occasionally, without colouring, for 10 minutes.
Fry until light golden in colour, add the mince and cook, stirring, until it's lightly browned.
Dry-fry for two to three minutes, stirring, until starting to colour, then roughly chop and mix with the sausage.
Chop the remaining hazelnuts into rough halves, stir them through the purée, then cook over a high heat, stirring all the time, until the colour darkens and the mixture thickens enough to hold its shape.
Onions, whether small and whole or large and sliced, need a low temperature if they are not to burn and blacken, and plenty of stirring to prevent them colouring unevenly.
Let them colour very slightly, for about 10 minutes, stirring regularly.
Warm it over a moderate heat, then add the spring onions, ginger and garlic and leave to soften, stirring so they do not colour.
Also, the colour loss can be reversed a bit by stirring through some freshly chopped sorrel just before serving.
