Preheat the oven to 350 F. In a medium bowl, whisk together flour, salt, and baking soda. In a large bowl, mix together butter and sugar until fluffy. Add in the egg and vanilla extract and mix until smooth.
Add in the flour mixture and mix until it is fully combined. Divide the cookie dough into two bowls. Mix one with red food coloring and one with green. In a shallow dish, combine granulated sugar and ground cinnamon.
Take a small amount of each cookie dough and roll together into balls. Roll the cookies into the cinnamon sugar mixture. Place the cookies onto a large ungreased baking sheet at least 2-inches apart. Bake for 10-12 minutes.
