Preheat the oven to 350℉. Coat a 9-inch square baking pan with cooking spray and place a parchment sling into the pan for easy removal. Set aside.
In a medium bowl, sift together the almond flour, tapioca flour, cocoa powder, and salt. Set aside.
In a large mixing bowl or in a stand mixer fitted with the whisk attachment, beat the eggs on medium-high speed for 3 to 4 minutes until they are pale yellow and fluffy. Add the avocado oil, maple syrup, coconut sugar, coconut milk, vanilla extract, vinegar, and baking soda. Beat on medium to combine.
Reduce the speed to medium-low and, working in increments, slowly add the dry ingredients to the wet ingredients, scraping the sides of the bowl as needed. Mix for 1 to 2 minutes until everything is well combined. Add the red food gel and mix once more.
Pour the batter into the prepared baking pan. Transfer to the oven and bake until the top is lightly browned and a cake tester inserted in the middle comes out clean, about 25 minutes. If the top starts to get overly browned, place a sheet of foil over the top, but do note this is a darker cake.
Remove from the oven and allow the cake to cool in the pan for 10 minutes. Use the parchment sling to carefully transfer the cake to a wire rack to cool completely.