Use sharp kitchen shears to trim and halve your chicken lengthwise, giving you 4-6 thinner pieces (depending on size). Place the chicken in a large bowl or a baking dish.
Dice up half of a jalapeño. Combine the diced jalapeño, lime juice, 2 tablespoon olive oil, and spices in a small bowl.
Pour marinade over the chicken and toss to coat. Let the chicken sit and marinate while you make the salsa.
Make the salsa
Cut up the mango, tomato, onion, and jalapeño, placing them all in a large bowl. Stir in the lime juice, then season with sea salt to taste.
Move the bowl of mango-tomato salsa to the refrigerator, allowing its flavors to meld while you cook up the chicken.
Cook the chicken
Heat 1 tablespoon olive oil in a cast iron skillet over medium-high heat for one minute, or until shimmering. Cook the seasoned chicken over medium-high heat for about five minutes a side, or until cooked through.
Serve the chicken & salsa
Remove the salsa from the fridge and stir. Top chicken with mango-tomato salsa, and enjoy! Optional: Serve garnished with chopped fresh cilantro or parsley.
Notes
The sweetness of the mango and tomato here cut the slight spiciness of the single jalapeño, but if you are very sensitive to spice you can use less pepper or de-seed it.