Zest and juice the lemons - Two medium size lemons should be enough.
In a small bowl add the flour, baking soda, baking powder and cornstarch: whisk to combine and set aside.
In a medium bowl, add the sugar and lemon zest. Rub the sugar and zest together until well combined.
Add the room temperature butter to the sugar mixture. Blend on high with a handheld mixer until fluffy and creamy- about 2 minutes.
Add the yogurt, lemon juice, vanilla extract and continue blending at high speed until well combined - 30 seconds to 1 minute.
Add the dry ingredients to the wet ingredients, blending at medium speed until just combined.
Scoop 3 tablespoon size dough balls and place them on a parchment lined pan. Place the pan in the refrigerator while the oven preheats.
Preheat the oven to 350 F, line 2 cookie sheets with parchment paper and prepare the rolling sugar. Add the sugar and zest to a small bowl, rubbing the sugar and zest together until well combined.
Once the oven reaches temperature, remove the dough balls from the refrigerator. Roll each dough ball between your palms to smooth them out, roll them in the lemon sugar and then place them on a prepared pan.
Bake the cookies for 13 minutes or until set. Let them cool on the pan for 5 to 10 minutes before transferring them to a cooling rack.
Store the cookies in an airtight container at room temperature.