1. clean (don't peel) heavy, firm sweet potato(es) - they should all be about the same size
2. prick the tops a few times with a fork
3. place directly on oven rack, with some space between each one - a cookie sheet or something can go on the lowest rack, to protect the oven from drips
4. set temperature to 450 and bake until your kitchen smells rly nice, some liquid is oozing out of the pricked places ~half an hour? longer? depends how big they are
5. turn off oven and let everything cool a for at least ~20 min