In a large skillet, cook beef and onion over medium heat until meat is no longer pink; crumble meat; drain. Stir in taco seasoning and water. Bring to a boil. Reduce heat; simmer, uncovered, for 5 minutes, stirring occasionally. Remove from the heat; cool slightly., Preheat air fryer to 375°. In a large bowl, combine cheese, sour cream and chiles. Stir in beef mixture. Place an egg roll wrapper on work surface with a corner facing you. Place 1/3 cup filling in center. Fold bottom one-third of wrapper over filling; fold in sides. , Brush top point with egg white; roll up to seal. Repeat with remaining wrappers and filling. (Keep remaining egg roll wrappers covered with waxed paper to keep them from drying out.), In batches, place chimichangas in a single layer on greased tray in air-fryer basket; spritz with cooking spray. Cook until golden brown, 3-4 minutes on each side. Serve warm with salsa and additional sour cream.