Special equipment: a pizza peel; a wood-burning pizza oven, optional; a pizza stone, optional
Four hours before cooking, heat a wood-burning pizza oven. Alternately, heat a pizza stone in a 500 degree F oven for 1 hour.
For the pizza dough: In a stand mixer fitted with the dough hook, combine the yeast, lukewarm water, and 1/2 cup of the bread flour. Mix well and let sit for 30 minutes, or until bubbly like foamy beer.
In a separate medium bowl, whisk together the remaining 3 1/2 cups bread flour and the salt until evenly combined.
Add 3/4 cup cold water and the olive oil to the yeast mixture. Turn on the mixer and begin adding the flour mixture in increments, then mix for 5 minutes, until the dough starts creeping up the dough hook and detaching from the sides of the bowl.
Grease a large bowl with oil and transfer the dough to the bowl. Turn the dough to coat its surface with oil. Cover the bowl loosely with a tea towel. Let the dough rise until doubled in size, about 2 hours. Punch the dough down, then let rise another 1 hour.
Sprinkle some all-purpose flour on your pizza peel. Using a rolling pin, stretch your dough to a very thin 12- by 6-inch oval.
For the filling: Lay the dough lengthwise on the peel. Starting from the top of the dough, lay the Taleggio slices in an even layer down the center of the dough. Put the sliced radicchio on top of the cheese.
Fold the left side of the dough over the filling. Then fold over the right side. Pinch the seams and the ends of the dough together to ensure that no filling is exposed. Gently turn the roll seam-side down, then push the ends of the roll towards each other to create a U-shape.
Gently place pizza roll on the oven floor and cook until the dough is golden and firm, 5 to 7 minutes. (If using a home oven with a pizza stone increase the baking time by 10 minutes.) Slice and serve.