Place the brussels sprouts in a large pan of boiling water and boil for 3-4 minutes until nearly tender. Drain and plunge into cold water to refresh, then drain again.
Meanwhile, melt half the butter in a frying pan over a medium-high heat, add the black pudding and fry until crisp all over. Add the lemon zest and set aside.
When you are ready to serve the dish, melt the remaining butter in a large frying pan over a medium heat, then add the brussels sprouts and black pudding and warm them through over a low heat. Tip into a serving bowl, then serve with the haggis-stuffed turkey.