Heat heavy skillet or grill over medium low heat.In a medium bowl, mix flour, salt, baking powder, and sugar. Set aside. In a separate bowl, mix evaporated milk, juice of 1 lemon (more if lemon isn't very juicy), and lemon zest. Allow to sit for five minutes, then add egg, vanilla, and melted butter. Mix to combine. Pour wet mixture into dry ingredients. Stir gently to combine. Splash in more evaporated milk if mixture is overly thick. Stir in blueberries. Again, check to make sure mixture isn't overly thick.Melt butter in heated skillet. Drop batter by 1/4 cup measures and fry pancakes on both sides until golden. Serve with softened butter and warm syrup.