Combine the jelly and pineapple juice in a small saucepan. Cook over low heat, stirring occasionally, until melted and thoroughly heated. Sprinkle chicken with pepper. Coat a large skillet with cooking spray; place over medium-high heat until hot. Add chicken and saute 4 to 5 minutes, turning once, until cooked through.
Spoon sauce onto individual plates. Top with chicken and a dollop of sour cream.