In a small bowl, combine 1 tablespoon olive oil, half the lime zest, half the lime juice, chili powder, cumin, salt & pepper. Add the chicken breast to the lime mixture and marinate for 15-20 minutes.
Meanwhile, bring the chicken broth to a boil. Once boiling, add the brown rice. Reduce to a simmer, cover, and cook for 10 to 20 minutes or until rice is tender Stir in the remaining lime zest and lime juice, scallions, cilantro, and diced mango. Set aside.
Heat large skillet over medium-high heat. Add remaining 1 tablespoon of olive oil.
Sear chicken on both sides, about 2-3 min each side, ensuring it is golden brown and slightly crisp on both sides. (Note: if using a non-stick skillet, chicken that may stick to the pan will
"Release" when it is ready to turn. No need to force it.
When chicken is golden brown on both sides, reduce heat to medium-low, pour in 1/4 cup water and cover.
Cook on medium-low an additional 6-8 minutes, until breasts are cooked through and no longer pink inside. Internal temperature should be 165 degrees.
Divide rice among 4 plates, top with chicken breast, and garnish with remaining lime slices.