Preheat the oven to 200 °C.
Wash the sweet potatoes and cut them into wedges. No need to peel them!
Use a peeler to create thin strips of lemon zest. Remove the rosemary from the sprigs and chop finely.
Mix all ingredients in a bowl.
Lightly grease a baking tray or use baking paper, then place the sweet potato slices on it. Bake them in the oven for about 40 minutes.