Preheat the oven to 300°. Line a baking sheet with parchment or a silpat and set aside.
Add the flour, sugar, baking soda and salt to a large bowl and whisk together.
Cut the butter into 1 tablespoon pieces and add to the flour mixture. Add the vinegar (it will start to fizz).
Use a hand mixer to blend the butter and vinegar evenly into the dry ingredients until a crumbly dough forms. Use a 1 teaspoon measure to drop rounds of dough onto the prepared baking sheet at least 3 inches apart (I use a mini cookie scoop for uniform cookies)-- the cookies will spread out in the oven.
Place a whole pecan in the center of each round of dough and gently press into the surface. Bake the cookies for 12-15 minutes or until the edges are just slightly golden.
Let the cookies cool for 2-3 minutes on the sheet pan before transferring to a wire rack to cool completely. Store in an airtight container, in a single layer, separating each layer with a piece of parchment paper.