Preheat your oven to 425°F (220°C) and line a large rimmed baking sheet with parchment paper for easy cleanup.
Dice the small potato into 1/2-inch cubes and cut the chicken breast into 1-inch bite-sized pieces.
In a large mixing bowl, whisk together the olive oil, lime juice, chili powder, cumin, garlic powder, sea salt, and black pepper.
Add the chicken, potatoes, sliced bell peppers, and diced red onion to the bowl, tossing thoroughly until every piece is coated in the spice mixture.
Spread the mixture in a single, even layer on the prepared baking sheet, ensuring the pieces aren't overcrowded to allow for maximum crispiness.
Roast in the center of the oven for 20 to 25 minutes, tossing the ingredients halfway through, until the potatoes are tender and golden and the chicken is cooked through.
Remove from the oven and garnish with freshly chopped cilantro before serving warm.