Mix the flour, salt, baking powder and baking soda in a small bowl. Set aside.

Beat the butter with the sugar until light and creamy.

Zest both lemons and extract about 2 tablespoons of juice - about half a large lemon. Set aside ¼ of the zest in a separate bowl.

Mix the remaining zest, lemon juice, egg, and vanilla extract in the butter/sugar mixture and mix until well incorporated.

Slowly add the flour mixture to the wet ingredients one cup at a time. Mix until combined.

Mix the zest you set aside with some sugar for rolling.

Take a tablespoon of the dough and roll into a ball between your hands. Roll the ball in the lemon sugar.

Place the ball on a baking sheet lined with parchment paper. Repeat the the remaining cookie dough, leaving about 2 inches between each cookie.

Bake for 8 - 10 minutes, or until the edges of the cookies start to get a nice golden brown.

Cool the cookies on the baking sheet for a minute before transferring to a cooling rack.