Put the butter or oil in a medium to large skillet
over medium-high heat. When the butter is melted or
the oil is hot, add the scallion and cook, stirring, until
softened, about 5 minutes.
Add the barley and cook, stirring, for a minute or
so, until glossy; add the herb, stock, and salt and pepper.
Bring to a boil.
Turn the heat down to low, cover, and cook for 30
minutes. Check the barley’s progress: It’s done when tender and all the liquid is absorbed. Continue to cook if necessary, adding a tablespoon or two more liquid if all the liquid has been absorbed and the barley is not quite done. If the barley is tender but a little liquid remains, cover, remove from the heat, and let rest for 10 minutes.
If 1/4 cup or more of liquid remains (unlikely), uncover,
raise the heat a bit, and cook, stirring, until the barley is
fluffy and the liquid evaporated. Fluff with a fork, garnish with parsley, and serve.