In a medium-sized bowl, add raisins and boiling water, and let raisins soften and plump up a bit while you continue prepping cookie ingredients. *This isn't a necessary step, but your cookies will be more moist if you take the time to do this.
Make the flax egg: In a small bowl, combine the ground flax meal and water and give it a stir. Set aside for 15 minutes to thicken.
In the bowl of a stand mixer fitted with a paddle attachment, or using an electric hand mixer and a large bowl, beat the softened vegan butter on medium speed for 1 minute. Add brown sugar and granulated sugar, and mix again for 2 more minutes, until fluffy and lighter in color. Pour in prepared flax egg and vanilla extract, and mix until well combined.
In a separate medium bowl, whisk together the flour, baking soda, cinnamon, and salt. Pour dry ingredients into bowl with the wet ingredients, and mix on low speed just until flour is incorporated.
Drain the raisins, and gently pat dry with a paper towel, being careful not to mash them. Add the raisins and oats into the cookie dough, and use a rubber spatula to mix until well combined in the dough. Chill cookie dough for 30 minutes in the fridge. (This isn't a mandatory step, however, your cookies will have a much chewier texture if you chill them.)
Preheat oven to 350 degrees F, and line two large baking sheets with parchment paper.
Using a 1-inch cookie scoop or teaspoon, scoop cookie dough onto baking sheet, for a total of 12 cookies on one baking sheet and 6 on the other.
Bake cookies for 12-14 minutes, until the edges are golden brown (the tops won't brown too much). Allow the cookies to cool on the baking sheet for 5 minutes, then use a spatula to transfer them to a cooling rack.