Chorizo stew

200g unsmoked bacon or rashers, chopped into lardons

2 medium onions, finely diced

6-8 garlic cloves, thinly sliced

2 tbsp tomato purée

1kg firm waxy potatoes, peeled and cut into medium chunks

800g Spanish cooking chorizo, cut into rounds

600g chestnut mushrooms, sliced

1.8l good chicken stock

½ tsp cayenne pepper

2-3 tbsp hot smoked Spanish paprika

sea salt

250g sour cream

juice of ½ lemon or 1 lime

handful of dill, finely chopped