Heat oil (1 1/2 inches) to 375°F in 4-quart Dutch oven or deep saucepan. Heat water and butter to rolling boil in 3-quart saucepan. Remove from heat; quickly stir in flour and salt. Stir vigorously over low heat until mixture forms a ball. Remove from heat; beat in eggs, 1 at a time, until smooth and glossy.