Preheat the oven to 350 F. In a medium bowl, whisk together flour, cocoa powder, salt, and baking soda. In a large bowl, combine butter with sugar until fluffy. Add in egg and vanilla extract and mix until smooth.
Add in the flour mixture until it is fully combined. Add in food coloring. Place powdered sugar into a shallow dish. Roll the cookie dough into balls and roll each one into the powdered sugar.
Place cookies onto a large ungreased baking sheet at least 2-inches apart. Bake for 10-12 minutes. Remove from the oven and top each one with a chocolate kiss.