A method of operating a burner assembly is provided. The method generally includes transporting combustible fuel and atomization air through concentric fluid lines of the burner assembly; mixing the combustible fuel and the atomization air to atomize the combustible fuel; adjusting a flow of the combustible fuel and the atomization air to obtain atomized fuel with an air-to-fuel atomization ratio of less than 0.6; outputting the atomized fuel from a nozzle of the burner assembly; and igniting the atomized fuel to produce a flame. A burner assembly operable by the method, and a corresponding nozzle are also provided.