PREPARE WEBER (kettle) barbecue for indirect cooking at moderate heat (normal fire).
Peel sweet potatoes and cut into thick slices.
1.Arrange in layers in shallow greased tray.
Sprinkle over combined sugar and mixed spice; dot with butter.
2.Sprinkle over the orange juice.
3.Cover tray with foil, place on top grill of barbecue, replace lid, cook 20 minutes.
Remove foil and test with a sharp knife; cook a few more minutes, if necessary.
Sprinkle over a little more orange juice if potatoes begin to dry out.