Wash hands with soap and water for 20 seconds.
Do not taste or eat any raw dough or batter made with uncooked flour and/or raw eggs.
Preheat oven to 400°F.
In a large bowl, mix flour, salt, baking powder, and sugar. Add the butter and cut into flour mixture using a pastry cutter until mixture looks like fine crumbs.
Heat up the milk on the stovetop in a small saucepan until warm, but not hot.
Remove the pan from the heat. Add the vanilla and lemon juice, then set aside for a moment.
Line a baking sheet with parchment paper and put it in the oven.
Add the milk mixture to the dry mixture and combine them quickly with a fork.
Scatter some flour on the work surface and tip the dough out. Dredge the dough and your hands with a little more flour, then fold the dough over 2-3 times until it's a little smoother. Don't overwork the dough. Pat into a round circle about 1/2 inch high.
Use a pizza cutter or knife to cut into 8 equal-sized triangle wedges.
Brush the tops with egg wash, then carefully place them onto the hot baking tray.
Bake for 10-15 minutes until risen and golden on the top.
Remove from the oven and let cool on the baking sheet for 2 minutes before transferring to a wire rack.
Eat just warm or cold on the day of baking generously topped with jam and clotted cream or homemade whipped cream.