Prepare grill with medium coals or heat broiler. Heat oil in 10-inch nonstick skillet over medium-high heat. Add onion; cook 4 to 6 minutes, until softened. Add 1/4 cup cider, apples and curry powder; cook for 4 minutes.
Add remaining cider, water-jelly mixture, vinegar and salt; simmer, stirring, 3 minutes. Stir in cornstarch mixture; cook, stirring, until sauce thickens and clears, 4 minutes. Remove from heat; divide sauce in half.
Alternately skewer shrimp and green onion on 4 metal skewers. Brush half of sauce over skewers. Grill or broil skewers 5 inches from heat, turning once, until the shrimp are opaque and cooked through, about 5 minutes. Serve with the remaining half of the reserved sauce.