There are still a fair few blackberries left in hedgerows in some parts of the country, but you could easily apply this to sloes or rose hips or blackcurrants. You can also get away with using frozen berries if necessary.
2-4 medium chillies, roughly chopped
450g caster sugar
Place the blackberries, chillies and sugar together in a large, heavy-bottomed saucepan and gently bring to the boil, stirring continuously. Using a ladle, remove any scum that rises to the surface and discard.
Allow to simmer for 1 hour, then pass through a fine-meshed sieve. Pour into a mould and leave to set in a cool place. You should have enough to fill about a ¼ litre jar to use at your leisure.
This jelly goes really well with cheese, pâtés and terrines, or can even be used to glaze a roast.