In a large saucepan, heat butter over medium heat. Add onion; cook and stir 3-4 minutes or until tender.
Stir in flour until blended. Gradually add milk and broth. Bring to a boil; cook and stir 2 minutes or until thickened. Remove from heat; stir in turkey, sweet potato, salt, pepper and cayenne. Refrigerate, covered, 2 hours or until firm.
Meanwhile, in a small bowl, toss apple with lemon juice. Stir in remaining salsa ingredients. Refrigerate, covered, at least 1 hour.
For croquettes, in a shallow bowl, beat eggs and water. Place flour and bread crumbs in separate shallow bowls. Shape turkey mixture into 1-1/2-in. balls. Roll in flour; shake off excess. Roll in egg mixture, then in crumbs, patting to help coating adhere.
In an electric skillet or deep-fat fryer, heat oil to 375°. Fry croquettes, a few at a time, 1-2 minutes on each side or until golden brown. Drain on paper towels. Serve with cranberry salsa.
Wear disposable gloves when cutting hot peppers; the oils can burn skin. Avoid touching your face.