Pat chicken dry with paper towels; season all over with salt and pepper. In a small bowl, combine cumin, oregano, garlic powder, and cayenne. Rub mixture into chicken.

In a large skillet over medium-high heat, heat oil. Add chicken and cook until golden, about 5 minutes per side. Transfer to a plate.

In same skillet over medium heat, cook onion and bell pepper, stirring occasionally, until softened, about 7 minutes. Add garlic and cook, stirring, until fragrant, about 1 minute more, then stir in tomato paste.

Add rice and cook until well coated and toasted, about 3 minutes. Add broth, diced tomatoes, bay leaf and ½ teaspoon kosher salt, stirring up any bits from bottom of pan. Bring to a boil, then add chicken back to skillet. Reduce heat and let simmer, covered, stirring occasionally so rice doesn't stick to bottom of skillet, and adding more broth or water if needed, until chicken is cooked through and rice is tender, about 30 minutes.

Remove bay leaf. Taste and season with more salt as needed. Top with cilantro.