Remove the leaves and outer skin of the pineapple with a sharp knife. Be sure to remove the hard round 'eyes'.
Cut off the central core and discard
Chop half the pineapple into small pieces and set aside.
Put the rest of the pineapple with the chillies and their seeds, garlic, ginger and fish sauce in a blender and blitz to a fine puree.
Put the puree into a deep, heavy-bottomed pan and add the sugar and wine vinegar. Bring to the boil slowly, stirring as you go.
When it comes to the boil, turn down to a simmer and add the diced pineapple. Skim off any foam that rises to the surface and cook gently for up to 1 hour, stirring from time to time, to prevent the mixture catching and burning.
When the mixture seems thick to the stir of a wooden spoon, decant it into a warm sterilised jar and seal.
Store in a larder or cool place, not in the fridge, for up to 9 months.
Once opened keep in fridge.
Scrape the sides of the pot too so that everything cooks evenly. The mixture thickens as it cooks.