Place the flour, salt and sugar in a food processor and pulse 3-4 time to combine.
Cut the butter into 1/2” squares and add it to the flour and pulse 8-10 times.
Add the sour cream and pulse until the dough just starts to come together. It will look like large clumps or curds.
Remove from the food processor, gather the dough together and form into a round disc. Wrap in plastic and chill in the fridge for 2 - 24 hours.