1. Heat the oven to 190 Degrees C.

2. Peel and dice the sweet potatoes and place in a saucepan. Cover with water and bring to the boil. Simmer, covered for 8-10 minutes until the potatoes are tender.

3. Drain well and spoon into a casserole.

4. Mix the sugar with the lemon rind and lemon juice, and spread this mixture over the top of the potatoes.

5. Dot the top with butter or margarine and bake for 35 minutes in the oven.