Boil cut-up sweet potatoes or bake at 350 degrees F (175 degrees C) whole sweet potatoes until tender.
In a frying pan, melt the butter and brown sugar together until bubbly. Add the orange juice and stir until smooth. Add the cut-up sweet potatoes and cook slowly, turning occasionally until the sweet potatoes are caramelized, about 20 minutes. If syrup is too thin, add a bit more brown sugar.