Preheat the oven to 350 degrees Fahrenheit/180 degrees Celsius. Prepare two cookie sheets by lightly oiling them or lining with parchment paper. If you have only one cookie sheet, just bake the cookies in batches.
Make the flax egg by whisking together the flax meal and 3 tablespoons water in a bowl. Set aside.
In a large bowl, beat together the sugar, vegan butter, pure vanilla extract and vinegar with an electric hand mixer until fluffy, about a minute. You can also do this using the whisk attachment on a stand mixer.
Beat in the flax egg for a few seconds until incorporated.
Add the dry ingredients to the wet ingredients-- flour, cinnamon, baking soda, baking powder and salt. Mix with a spatula until the cookie dough comes together.
Stir in the rolled oats and raisins until they are evenly dispersed. Don't overmix.
Lightly grease a cookie sheet or line it with parchment paper. Use a 1 ½ tablespoon cookie scoop or a spoon to drop balls of cookie dough on the baking sheet, leaving at least two inches between each cookie because these will spread.
Bake in the preheated oven for 14 minutes. For crispier cookies, bake a couple of minutes longer. Rotate the sheets halfway through baking. If baking two sheets at a time, also move the sheet from the upper rack to the lower rack and vice versa halfway through.
Let the cookie sheet stand on a wire rack for 5-10 minutes until the cookies are firm enough to transfer directly to the wire rack with a spatula. They will continue to firm up as they cool.