Heat half of the oil in a large, heavy based pan, and brown the chicken all over. Transfer them to a plate.
Meanwhile, finely chop the onion and garlic. Cut the chorizo into 1cm cubes.
Heat the remaining oil in the same pan, fry the onion and garlic, add the sausage pieces, then stir-fry for 3-4 minutes.
Pour over the wine, and reduce it by half. Add the tinned tomatoes, chicken stock, thyme leaves, bay leaves and sugar.
Put the chicken pieces into the sauce - the sauce should completely cover the meat!
Cook under a lid for 20 minutes.
Meanwhile, cut the potatoes into bite-sized chunks.
After 20 minutes of cooking, add the potatoes and olives, then let it simmer on the stove for 35 minutes.
Serve warm with thyme leaves scattered on top.