Pat the chicken breast completely dry with a paper towel to ensure a proper sear.
In a small bowl, combine the chili powder, cumin, garlic powder, sea salt, and black pepper, then rub the mixture evenly over both sides of the chicken.
Heat the avocado oil in a cast-iron skillet over medium-high heat until it begins to shimmer.
Place the chicken in the skillet and sear for 6 to 7 minutes per side, or until a deep golden-brown crust forms and the internal temperature reaches 165°F.
While the chicken cooks, place the corn kernels in a separate dry non-stick pan over high heat for 3 minutes, stirring occasionally until lightly charred.
In a medium mixing bowl, whisk together the Greek yogurt, lime juice, and smoked paprika until the sauce is smooth and creamy.
Fold the charred corn, crumbled feta, and chopped cilantro into the yogurt sauce until well combined.
Remove the chicken from the heat and let it rest for 5 minutes before slicing against the grain.
Serve the sliced chili-lime chicken immediately alongside the creamy street corn salad.