Bring the sour cream to room temperature. Prepare two large cookie sheets by lining with parchment paper. Melt the butter in medium saucepan over medium heat. Add the sour cream and stir until smooth. Add the sugar, brown sugar and salt, and stir until sugar dissolves. Attach a candy thermometer to the pan, increase the heat to medium high, and boil, stirring constantly, until mixture reaches 234 degrees (soft-ball stage). Remove the pan from heat and let the mixture cool to 200 degrees. Stir in the pecans, cinnamon and vanilla. Continue stirring until mixture thickens and loses its gloss, but is still fairly liquid. This will take about 2 to 3 minutes. Spoon the mixture onto the prepared baking sheets into individual candies about 2 inches in size. If the mixture is too runny, stir until thicker. If it is too thick, stir in 1/2 teaspoon warm water.