Preheat the oven to 375°F/190°C. Line a baking sheet with parchment paper.
Cookie dough: To create the flaxegg, combine the hot water and flax meal. Set aside. In a large bowl beat the vegan butter with granulated sugar and light brown sugar for 2-3 minutes or until light and fluffy. Add the vanilla extract and the flaxegg. In another bowl combine all-purpose flour, cream of tartar, baking soda, ground cinnamon and salt. Whisk to combine. Transfer the dry ingredients into the bowl with the wet. Fold to combine.
Bake: Roll the cookie dough into around 1 1/2 tbsp amounts. To make the coating, combine the granulated sugar and ground cinnamon in a wide bowl. Roll all 12 cookie dough balls into the cinnamon sugar mix. Place onto the pre-lined baking sheet. Keeping a 2-inch distance between each cookie. Gently press down the cookie dough ball with the back of a spoon. Sprinkle a little more of that cinnamon sugar mix. Bake for 10-11 minutes. Allow to cool on the baking sheet for 10 minutes, then transfer onto a cooling rack to cool for 5ish minutes more. Enjoy!