In a food processor, combine the flour, salt, and sugar. Pulse until mixture is incorporated. Add the butter, and process until the mixture resembles coarse meal, about 10 seconds. Add herbs, and pulse to combine. With the machine running, add the ice water through the feed tube, in a slow, steady stream, until dough just comes together. Do not process for more than 30 seconds.
Turn out dough onto a lightly floured work surface. Divide into two pieces, with one piece slightly larger than the other. Flatten into 1/2-inch-thick discs. Wrap in plastic, and chill at least 1 hour or overnight.