Directions: Place butter, and lime and orange rinds in a large mixing bowl and beat until light and creamy. Add sugar a little at a time, beating well after each addition.
Beat in eggs one at a time and mix well. Fold through flour alternatively with yogurt. Spoon mixture into a greased 20cm/8 in rind tin and bake for 30-35 min, or until cooked. Stand in cake tin for 5 min, then turn out onto the wire rack with a tray underneath.
To make syrup, place lime juice, orange juice and sugar in a saucepan. Cook over a medium heat, stirring occasionally, until sugar dissolves. Bring mixture to the boil without stirring, and boil for 3 min. Remove from heat and pour hot syrup over the hot cake. Set aside to cool.