Whisk the flour, baking soda, cream of tartar, and salt in a bowl.
Beat the softened vegan butter and brown sugar until smooth, then mix in the maple syrup and vanilla.
Add the dry ingredients and stir just until a soft dough forms. Chill for 30 minutes.
Heat the oven to 350°F and line two baking sheets. Mix the granulated sugar and cinnamon in a shallow bowl.
Scoop the dough into 18 portions, roll each into a ball, and coat in cinnamon sugar.
Bake for 10 to 12 minutes, until the edges are set and the centers still look slightly soft. Cool on the sheet for 10 minutes, then transfer to a rack.
Notes
Let the cookies finish setting on the baking sheet; moving them while hot can cause breakage.