Sprinkle sugar in an 8-inch round cakepan. Place over medium heat, and cook, tilting pan or stirring until sugar melts and turns a light golden brown. Remove from heat. (Mixture may crack slightly as it cools.)
Process condensed milk and next 6 ingredients in a blender 15 seconds; pour over caramelized sugar. Cover pan with aluminum foil, and place in a 13- x 9-inch pan. Pour hot water into larger pan to a depth of 1 inch.
Bake at 350° for 1 hour or until set. Remove pan from water; uncover and cool in pan on a wire rack at least 30 minutes. Cover and chill 8 hours. Loosen edges with a thin knife. Invert flan onto serving plate; arrange orange sections on top.