Weigh your flour; or measure it by gently spooning it into a cup, then sweeping off any excess. Combine all of the dough ingredients, and mix and knead them together — by hand, mixer, or bread machine — until you've made a soft, smooth dough. Allow the dough to rise, covered, for 1 hour., Roll the dough into a 12" x 18" rectangle., Brush all over with mustard, leaving a 1" mustard-free zone all around the edge., Add the cheese in a single layer, then the ham; again, leave the border bare., Starting with a long edge, roll the dough into an 18" log. Pinch the long seam closed, then fold the ends over and pinch them closed, too., Curve the log into a horseshoe shape on a lightly greased or parchment-lined baking sheet, seam-side down., Cover the sheet, and allow the roll to rise for 1 1/2 to 2 hours; it should look puffy, though not doubled. Towards the end of the rising time, preheat the oven to 375°F., Slash the roll crosswise, about 1/2" deep, at 3" to 4" intervals along its length. There's no need to use a knife for this; making snips with a pair of scissors works just as well., Bake the roll for 35 minutes, until it's golden brown, tenting it lightly with foil if it appears to be browning too quickly. Remove it from the oven, and allow it to cool for 20 minutes before serving.