1. Preheat the oven to 200 °C. Place the sweet potatoes in
a fireproof dish and bake in the middle of the oven until soft.
2. Peel ginger, grate finely and place in a bowl. Add butter, coriander, lime peel and juice and mix well. Season with salt.
3. Slice a cross into each sweet potato with a knife and add some ginger butter.