Place the oven rack in the lower third of the oven and preheat to 350 degrees Fahrenheit. Line a standard cupcake baking tin with cupcake liners.
Combine flour, salt, baking soda, baking powder, cinnamon, ginger, nutmeg, and Chinese Five Spice Blend in a medium bowl and stir with a whisk.
Combine water and flaxseed in a small bowl and set aside.
Combine roasted sugar, canola oil, stout, egg substitute, and eggs in a large bowl and beat with a mixer at medium-high speed until well blended.
Add the flaxseed mixture and sweet potato and beat on low speed until just blended.
Add the flour mixture and beat until combined.
Fill the cupcake liners 3/4 of the way up. Bake for 20 to 25 minutes until the center of the cupcake bounces back when you lightly press your fingers to it or a toothpick comes out clean.
Take the cupcakes out of the baking pan and let them cool completely on a wire rack before frosting.