In a small bowl mix the sugar and lemon zest together.
Rub the zest into the sugar, so it really coats the sugar crystals. Cream the butter and zest/sugar together in a stand mixer fitted with the paddle attachment.
Add the flour, salt, lavender, vanilla and mix until it starts to come together. Add the lemon juice and continue mixing until the dough is smooth.
Dump the dough onto a piece of parchment paper or a silicone mat.
Pat the dough into a smooth rectangle and then roll it under a sheet of plastic to a 1/4-inch-thick rectangle. Refrigerate for at least 30 minutes, but this can be done a day ahead.
Preheat oven to 300°F.
Cut the dough into equal size pieces. I did a 10×4 cut, but you can make them any shape or size you want.
Use a fork to score the tops. This doesn’t really do anything, but make a pattern, so you can get more creative if you like.
Spread out your lemon lavender shortbread a bit, since they will expand in the oven. Bake for about 20 to 30 minutes. This will depend on the shape and size. You only want to bake until they are just starting to turn golden on the bottom. They are traditionally very pale.