Place spring roll wrappers between two clean damp towels, to soften.
In a bowl, mix together chicken, crab, green onions, carrot, fish sauce, soy sauce, garlic and celery. Place a lettuce leaf in middle of each spring roll wrapper. Place a spoonful of chicken mixture on each lettuce leaf. Fold over three sides of wrapper to enclose filling. Roll up firmly.
Heat oil in a wok or deep-fat fryer to 190C (375F), or until a cube of bread browns in 40 seconds. Add rolls and fry, in batches, 3 minutes, or until crisp and golden. Drain on paper towels. Garnish with green onion flowers and serve with chile dipping sauce.