In a large pot, heat the vegetable oil over medium heat. Add the onions and cook until translucent - about 5 minutes. Add the garlic and cook, stirring frequently, for about 1 minute - being cautious not to burn it. Add the chicken broth and bring to a simmer. Add in the chicken, black beans, corn, salsa, rice, seasoned salt, and cumin. Stir to combine. Reduce the heat to low and cook for 5 to 10 minutes, or until the rice is tender.