POTATO-AND-RADICCHIO TART

Steps:

• After the dough has rested in the fridge for at least an hour, and up to 12 hours, preheat the oven to 350. Roll dough into a 12-inch circle, dusting with flour underneath and on top, as needed. Use a knife to trim the rough outer edge of the circle, cutting away as little dough as possible. Place the disc on a sheet of parchment paper, on a half-sheet pan. Use a small palette knife or spoon to spread the ricotta across the dough almost all the way to the edge, and scatter the provolone and lemon zest on top. Season lightly with salt and pepper. (If the dough is warm, return it to the fridge while you prepare the potatoes.)
• Use your hands to roughly break apart the potatoes, so they're about halved, with jagged edges. In a large bowl, mix the potato pieces with olive oil, shallots, salt and pepper. Scatter the potato-shallot mixture all over the dough, and set the bowl aside (you'll use it to dress the radicchio). Fold an inch at the edge of the dough inward, pressing it over the potato mixture, working your way around the whole tart. Brush the dough with egg wash, and bake for 45 minutes, or until the edge as well as the bottom are light brown and crisp.
• Grip the parchment paper, and slide the tart onto a cooling rack, then cover it with grated Parmigiano. When the tart is no longer hot to the touch, dress radicchio leaves using the same bowl you used for the potatoes, still slick with olive oil, adding another drizzle if needed and a splash of white-wine vinegar so the leaves are just barely coated and glistening. Arrange the leaves on top of the cooled tart, season lightly with salt and serve.