Heat oil in a medium saucepan over medium-high heat. Add the rice; sauté 3 minutes. Add onion; sauté 1 minute. Add broth, milk, salt, and pepper; stir. Bring to a boil; cover, reduce heat, and simmer 17 minutes or until liquid is absorbed and rice is tender, stirring once after 10 minutes. Stir in mint and cilantro; cover and let stand 5 minutes.