I wanted to show (with actual pictures) the ease of sprouting a sweet potato tuber at home. Simply take one the tubers from your local fruit and veg shop. Pop it in a bottle or clear(ish) container in the sink with water in the bottle. Suspend your tuber in the bottle with some toothpicks. The crazy eyes are optional but make you smile while washing the dishes!
Tubers take about 4 weeks to grow to a planting size of shoots of around 20-30cm long and create little roots in the water. Plant out into the garden when they are large enough leaving the shoots above ground.
I have heard of people who actually leave the tubers in the kitchen and harvest the shoots repeatedly to add to stir fires and salads.