Place the into a sieve and rinse with cold water. Drain.
Place the farro into a medium sized pot with a lid. Add the water or stock or a combination of both and add the salt and butter or olive oil if using. Bring to a boil over high heat.
Reduce the heat to low, cover, and gently simmer for about 30 minutes, until it is tender but still chewy (if you have soaked it overnight, the cooking time will be shorter). The cooking time depends on a number of factors, all explained above! If there is liquid remaining in the pot, drain it in a sieve.
If you are using it in a salad or a room temperature dish, spread it out on a rimmed baking sheet to cook to prevent it from getting mushy.