Preheat oven to 375* F. Line 2 baking trays with parchment.
In a large mixing bowl, combine sugar, oil, plant milk, agave, vanilla and lemon juice. Whisk to combine.
Put a sieve or sifter on top of the bowl, careful not to get the bottom of the sifter wet. Into the sifter, add flour, cocoa powder, baking powder, baking soda and salt.
Sift the dry ingredients into the wet ingredients and whisk to combine.
Portion the batter into about 2 tablespoon rounds leaving 2 inches of space between each cookie. Use the back of your scoop to gently swirl them to coax them into a circular shape if you need to. A cookie scoop will be really helpful here to keep them round if you have one. While the first tray is in the oven, portion batter onto the second tray.
Once you are done with one tray, insert onto the middle rack a a 375* oven for 9-11 minutes. To test for doneness, gently press the middle of a cookie. If it springs back, its done!
Remove the first tray from the oven and insert the second tray. Allow cookies to cool on the baking sheet for at least 7 minutes before transferring to a cooling rack to cool completely.
Once completely cool, fill with desired fillings and devour.