add the fat, and using a pastry cutter, cut up into pea sized chunks (if you don't have a pasty cutter, cut into small cubes and then add into the bowl), then use your fingers to work the fat into the flour until you have a crumbly mix with bits the size of small peas or grains of rice remaining.
add cold water - start with only 1/4 cup, and add the vinegar. mix in with a wooden spoon. if the mixture seems really dry, add the rest of the water. stir to combine, and then turn out onto clean counter top and gather the mixture together with your hands. it 