FOR DOUGH: Prepare pizza dough as recipe directs. Heat pizza stone in oven for at least 45 minutes before assembling pies: Place pizza stone on rack in lower third of oven. Heat oven to maximum temperature (500º to 550º).
While stone is heating prepare topping.



 

FOR TOPPING:Bring a medium pot of salted water to a boil. Meanwhile, place onion slices in a bowl and cover with cold water. Swish the water around; let onions soak 10 minutes, then drain. Repeat 2 or 3 times while you prepare the rest of the topping (soaking raw onion in cold water mellows the harsh bite). 

 

Add tomatoes to the boiling water; boil for 20 seconds. Drain tomatoes, then peel, quarter, seed and coarsely chop.

 

Rinse and pat dry leek. In a large skillet, heat oil over medium-high heat. Add leek and cook, stirring frequently, 2 minutes. Add tomatoes, 1/4 teaspoon salt and sugar; continue cooking, stirring occasionally, until sauce is blended and thickened, about 4 minutes more. Transfer sauce to a bowl.

 

ASSEMBLE PIZZA: On a lightly floured work surface, press 1 dough ball with your fingers to begin to shape into a round. Use your fist and hands to gently stretch dough to a 10-inch round. (A floured rolling pin can be used to help roll out dough.) Transfer dough to a lightly floured peel; gently shake peel to make sure dough does not stick.


 

Working quickly, spread 1/2 cup sauce over dough, leaving about a 1/2-inch border. Tear 1/4 of the cheese into pieces and arrange on top of sauce. Drizzle lightly with oil and sprinkle with salt. Slide pizza onto stone. Bake until cheese is melted and bubbling in spots and edge of crust is crisp and golden, about 7 minutes. 

 

Using the peel and a large spatula or pair of tongs, transfer pizza to a cutting board; top with capocollo and red onion. Serve hot. Repeat with remaining ingredients.