Preheat oven to 350 degrees F. Line two baking pans with silicone baking mats or parchment paper.
With a hand or stand mixer, beat together the butter and sugar until pale and fluffy, about 2 minutes. Add the egg and vanilla and beat until well combined.
In a separate bowl, whisk together the flour, cream of tartar, baking soda and salt until well combined.
Add the flour mixture to the butter mixture and mix on low until a smooth cookie dough is formed. Scrape down the sides of the bowl with a spatula as needed.
Gently fold the chopped strawberries into the cookie dough using a rubber spatula or wooden spoon. Be careful not to over mix.
Use a small cookie scoop to form the dough into balls. Place 12 cookie dough balls on each prepared baking sheet.
Bake the cookies for 12 - 14 minutes, until the edges are starting to lightly brown and the middles are nice and puffy.
Be sure to rotate the baking pans halfway through baking - front to back and upper rack to lower rack.
Allow the cookies to cool on the pans for 10 minutes. Use a cookie spatula to gently remove the cookies from the pans to a cooling rack.