Soused aromatic mackerel with onions, garlic and mint

2 pieces of star anise
½ teaspoon coriander seeds
½ teaspoon mustard seeds
4-5 allspice berries
½ teaspoon black peppercorns
6 cloves
A pinch of mace
2 small dried chillies
2.5cm fresh root ginger, peeled and chopped
2 bay leaves
150ml white wine vinegar
50ml water
50ml dry white wine
4 level tablespoons sugar
3 cloves of garlic, finely sliced

1 small onion, finely sliced
2 mackerel, filleted
A pinch of salt
A handful of fresh mint, chopped

Preheat the oven to 180c/350f/gas 4.  Put all the dried spices and the ginger (but not the bay leaves) into a pestle and mortar.  Give them a quick bash to break the seeds and berries open, then place in a saucepan with the bay leaves, vinegar, water, wine and sugar.  Bring to the boil and simmer for 10 minutes.  Strain and discard the spices, then add the sliced garlic and onions, cover and cook gently for a further 10 minutes until the onions have softened.  Place the fish flesh-side down in a casserole dish, sprinkle with a little salt and pour the spiced liquid over the top.  The fish should be just covered; top it up with a little water if necessary.  Cover the dish and bake in the preheated oven for 20minutes.  Removed from the oven, sprinkle with the mint and serve.