Spray ramekins with nonstick cooking spray.In a medium bowl, whisk together sugar and flour.In a second bowl, whisk together egg yolks and butter until well combined. Whisk in milk, lemon juice, and lemon zest. Pour egg yolk mixture into sugar mixture and whisk until smooth.Beat egg whites and salt in a mixer until firm peaks form. Gently fold egg whites into sugar mixture. Pour batter into prepared ramekins.Place CanCooker rack into the bottom of the CanCooker and add 12-16 oz water. Water should be below the rack. Place ramekins on the rack. Close lid and steam on low to low/medium heat for 20 minutes.Transfer ramekins to a cooling rack and let cool for 10 minutes. Serve with seasonal berries and whip cream.