Heat a large skillet over medium-high heat. Saute onion with sea salt and cayenne pepper until softened, about 7 minutes. Add ground turkey and garlic powder; cook and stir until turkey is no longer pink, about 5 minutes. Add black beans, water, green bell pepper, green chiles, and taco seasoning. Mix well. Reduce heat to low and let simmer with the lid on until flavors blend, 10 to 15 minutes.
Stir cooked rice into the turkey mixture; simmer until heated through, 3 to 5 minutes. Remove from heat and let stand for 10 minutes.