In a large (5- or 6-quart) pot or Dutch oven, heat the oil over medium heat. Add the onion, sprinkle with ¼ teaspoon salt, and cook until softened, stirring occasionally, about 3-4 minutes.
Turn the heat to medium-high, then add the chicken and sprinkle with remaining ½ teaspoon salt, garlic powder, paprika, and cumin, stirring to combine. Cook until the chicken is browned and just cooked through, about 5-7 minutes, stirring occasionally.
Add the tomato paste and the rice. Cook until fragrant, about 2-4 minutes, stirring frequently.
Add the stock and bring to a rapid boil. Cover, reduce to a low simmer, and cook for 15-18 minutes, or until the rice is just tender.
Remove the pot from the heat and allow it to sit for an additional 5 minutes. Uncover, add the lime juice, and fluff with a fork.
Serve with optional toppings, if desired.
Notes
The Right Pot: Make sure to use a large, heavy-bottomed pot with tight-fitting lid for best results.