Preheat your oven to 350 F and line a baking sheet with parchment paper. Set aside.
Next, prepare the flax egg. Mix your ground flaxseed meal with 1 tablespoon of water and set aside to thicken. This should take approximately 5 minutes.
While the flax egg is thickening, pour the dry ingredients into a bowl and stir to combine.
Next, add in the wet ingredients, including the flax egg, and mix to fully combine.
Use a spoon to form the dough into a ball, and transfer it to your baking sheet.
Lightly grease a spatula or the back of your spoon with a little oil, then press the dough down until a 1/2 inch thick cookie forms.
Bake for 13-15 minutes, or until it turns golden brown.
While the cookie bakes, prepare the icing. Mix together the lemon juice and powdered sugar or monk fruit sweetener until an icing forms. You can do this by hand or with a stand mixer.
Once the cookie is done, remove it from the oven and let it cool completely.
Top with the icing and garnish with additional poppy seeds and lemon zest, if desired.
Serve, and enjoy!