Bring broth to a boil in a large saucepan over high heat. Add rice and bring to a simmer; cover, reduce heat to medium-low and cook for 4 minutes. Stir in peas and return to a simmer over high heat. Cover, reduce heat to medium-low and continue to cook until the peas are hot and the rice has absorbed most of the liquid, about 6 minutes. Remove from heat and stir in scallions, feta, mint and pepper. Cover and let stand until the liquid is absorbed, 3 to 5 minutes.