Heat chicken stock in a saucepan until boiling; keep hot until ready to use.

Heat vegetable oil in a 2 quart saucepan over medium-high heat. Cook and stir onion and bay leaf in the hot oil until onion is tender, about 5 minutes.

Stir basmati rice into onion mixture until rice is coated with oil.

Pour hot chicken stock into the rice mixture. Season with salt; stir.

Bring rice mixture to a boil; cover and reduce heat to medium-low. Continue simmering until rice is tender and liquid is absorbed, about 20 minutes.

Remove saucepan from heat and discard bay leaf. Add butter and fluff the rice with a fork.