First, zest the lemon. Reserve juice to make a glaze with if desired.
Preheat the oven to 400°F.
In a medium bowl, whisk together the sugar and lemon zest until the sugar turns yellow and fragrant.
Add flour, salt and baking powder to the sugar mixture and mix to combine.
Add the strawberries to the flour mixture and toss to distribute evenly.
In a measuring cup, add the egg and enough heavy cream to fill 1 cup. Add vanilla extract and beat to combine.
Make a well in the middle of the flour mixture and pour in the liquid mixture.
Fold with a spatula or wooden spoon until a wet dough forms.
Turn the dough out onto a well-floured board, flour top of the dough and your hands, and pat the dough out about 1/2” thick. Fold the dough over itself and pat it out again, do this about 4 times.
Shape the dough into a rectangle and roll it out to about 5”x8” or 6”x9”.
Use a pizza cutter to cut the rectangle in half lengthwise, then cut in three crosswise to make 6 squares. Cut each square diagonally to make 12 triangles.
Place the scones on a parchment paper-lined baking sheet, brush the top and sides with the egg white, and sprinkle with coarse sugar.
Bake for 17 minutes until a toothpick inserted in the middle comes out clean.
Let cool completely on a wire rack.
If you'd like to make a glaze, mix a tablespoon of lemon juice with 1 cup of powdered sugar and drizzle over the top of the scones.