Make the strawberry sauce: Cook 3 cups chopped strawberries, 1/4 cup sugar, the juice of 1/2 lemon and 2 tablespoons water in a saucepan over medium heat, stirring, until the berries break down, 10 minutes. Stir in 1 teaspoon vanilla. Strain through a fine-mesh sieve, pressing on the solids; let cool. Meanwhile, make the pancakes: Whisk 1 1/2 cups flour, 3 tablespoons sugar, 1 tablespoon baking powder and 1/2 teaspoon salt in a large bowl. Whisk 1 1/4 cups milk, 1/2 stick melted butter, 2 eggs and a little vanilla in a medium bowl, then whisk into the flour mixture until just combined. Cook by 1/4 cupfuls in a hot buttered skillet until golden. Stack the pancakes, then drizzle with the strawberry sauce and insert a knife into the top.