Combine first 10 ingredients in a small bowl. Season with kosher salt and pepper and adjust seasonings to taste. Set aside while you prepare the chicken. Alternatively, the salsa can be prepared in advance, covered and stored in the fridge for up to 24 hours.
Heat the oven to 400 degrees. Combine the next 6 ingredients together in a small bowl (cumin, kosher salt, brown sugar, Spanish paprika, chili powder and fresh ground pepper). Set aside.
Using a meat tenderizer, gently pound each piece of chicken until it is about ½” thick. Rub each piece of chicken with spice mixture, coating all sides.
Heat an oven-proof grill pan, cast iron skillet or non-stick pan to medium high. Add olive oil and coat bottom of pan well. I use a paper towel to rub the oil into all the ridges to make sure my grill pan is well coated. Sear chicken on both sides and finish in the oven for 8 minutes.
Plate each piece of chicken and serve it with a couple heaping spoonfuls of the mango and corn salsa.