Peel and finely slice the onions, peel and finely chop the garlic, then deseed and finely slice the chillies.
Place the onions, garlic and chillies in a large pan over a low heat with a little oil and sweat down for 8 to 10 minutes, or until soft but not coloured.
Add the cranberries, sugar, vinegar and 50ml of water.
Simmer gently for 15 to 20 minutes, or until the berries are soft and breaking down but still just holding their shape.
Gently mash a little and cook for a further 15 minutes, or until thickened and jammy.
Season with sea salt, black pepper and a drizzle of oil, then allow to cool.
Spoon into sterilised jars and tuck in when it’s cooled. It keeps for 1 week.