Heat oil in 12” skillet over medium-high heat. Add chicken pieces. Cook until golden brown on all sides, about 5 minutes; transfer chicken to plate.
Add onions and peppers to same skillet. Cook, stirring occasionally, until onions are soft and translucent, about 5 minutes. Stir lemon juice, chili powder, garlic, paprika and hot pepper flakes into skillet. Cook until garlic is fragrant, about 30 seconds more. Return chicken to skillet.
Add contents of yellow rice mix and 2 cups water to skillet; stir to combine. Bring water to boil. Reduce heat to medium low. Simmer, covered, until chicken is cooked through, rice is tender and water is absorbed, about 25 minutes.
Remove skillet from heat; stir in cilantro. Serve warm.