1. Heat the oven to 425°. In a small glass or stainless-steel bowl, combine the pimientos with the vinegar and set aside.
2. In a large nonstick frying pan, heat the oil over moderate heat. Add the onions and salt and cook, stirring frequently, until golden, about 20 minutes. Remove from the heat and stir in the pimiento mixture.
3. Divide the onion mixture between the 2 pizza shells. Top each with half of the fontina, Roquefort, and Parmesan.
4. Bake the pizzas directly on the oven rack (for a crisper crust) or on two baking sheets until the cheese melts, about 15 minutes.
Wine Recommendation: The cheeses and sweet onions call to mind sangiovese's crisp cherry and herb flavors and high acidity. For a change, opt for a lesser-known Sangiovese di Romagna instead of Chianti.
Notes: If you prefer to start with store-bought pizza dough or your own homemade dough, simply follow the instructions in Step 1 of the recipe for Mushroom, Zucchini, and Swiss-Cheese Pizza, to prebake the crust before topping it.