In a large skillet, heat the oil over high heat. Add the chicken and cook, turning once, until browned, about 3 minutes. Add the coriander, and stir for about 30 seconds.
Add the chicken broth, lower the heat and simmer for 3 minutes, scraping up any browned bits; transfer to a plate. Add the coconut milk to the skillet, increase the heat and boil to reduce by half, about 4 minutes.
Stir in the mango and cook until warmed through. Return the chicken to the skillet, toss and remove from the heat; season with salt and pepper.
Meanwhile, in a medium saucepan, simmer the black beans over low heat. Stir in the lime juice and 3 tablespoons mint.
Divide the beans among 4 plates. Top with the chicken and remaining mint.