Combine broth, wild rice, scallion whites, and pepper in a large saucepan; bring to a boil. Cover, reduce heat and simmer for 10 minutes
Stir in brown rice; return to a boil. Cover, reduce heat and simmer until the rice is tender and most of the liquid is absorbed, 30 to 35 minutes more. Remove from heat and let stand, covered, for 5 minutes. Fluff with a fork and serve
Percentages are based on a diet of 2000 calories a day.