Preheat the oven to 180°C. Wash and trim brussels sprouts then cook for 8 minutes in a pan of boiling salted water, then drain well.
Dice Chorizo then place in a frying pan in olive oil and cook until crispy. Remove from pan and add to a roasting tray with roughly chop chestnuts. Add leaves from fresh rosemary sprigs and combine.
Add cooked brussel sprouts, sherry vinegar to the roasting pan and mix everything together. Roast for 25 minutes until brussel sprouts are starting to colour.
Servings 8