In a large skillet, sauté the chopped onion in a tablespoon of olive oil until translucent. Add the chicken breast to quickly brown it, then set aside. In the same pan, cook the sausage and the shrimp, separately, until browned. Set all meat aside.
In a large soup pot, bring 3½ cups water and ¼ cup vegetable oil to a boil. (The oil is optional, but it adds a silky texture that is really nice.) Add the rice/seasoning mix and the white rice, bringing back to a boil. Lower heat and simmer for about 15 minutes, stirring occasionally. Add the meats that have been cooked, and simmer for about 15 more minutes. Season with the chili powder and pepper to taste.
Add the red pepper slices with about 10 minutes to go. Cook until liquid has been absorbed and rice is tender.