Combine salsa, jelly and cornstarch in a small saucepan. Cook over medium-high heat, stirring frequently, until sauce boils and thickens, 4 to 5 minutes. Add Li'l Smokies; heat through, about 2 minutes.
Transfer mixture to a small slow cooker or fondue pot set on low heat to keep warm. Sprinkle green onion on top if desired. Serve with wooden tooth picks.