Combine frozen blueberries, 2 tablespoons water, lemon juice, and 2 tablespoons sugar in a small pot
Cook over low medium heat, stirring occasionally, for 5 to 7 minutes until thickened, then remove from heat
Whisk together 2 tablespoons sugar, egg yolks, milk, vanilla, and a pinch of salt
Sift the flour and baking powder over the yolk mixture and whisk until smooth
Whip egg whites with cream of tartar until frothy
Slowly stream in remaining 2 tablespoons sugar while mixing and continue whipping to stiff, glossy peaks
Fold in ½ of the meringue until 75% incorporated, folding lightly to keep it airy
Fold in the remaining meringue, stirring just until the last streaks disappear
Heat a non-stick skillet over low heat and grease with neutral oil, wiping with a paper towel to leave only a thin layer
Add the batter to a piping bag or resealable plastic bag and snip a large hole in the corner
Pipe tall mounds of batter into the pan, about ½ cup each
Add 1 teaspoon water and cover with a lid to steam, cooking for 8 minutes on low heat until pancakes have set
Carefully flip the pancakes and add another teaspoon of water, cover and finish cooking for 3 to 4 more minutes
Serve the pancakes with whipped cream and blueberry sauce
