Meanwhile, mix corn starch and 2 Tbsp. sugar in medium saucepan. Gradually stir in water. Bring to boil on medium heat; cook 8 min., stirring constantly. Remove from heat. Add dry jelly powder; stir 2 min. until completely dissolved. Stir in lemon juice and remaining zest. Refrigerate 40 min. or until slightly thickened, stirring occasionally.