Mollie Katzen's Vegatable and Walnut Pizza

1 cup warm water1 package (2 teaspoons) active dry yeastPinch of sugar#189; teaspoon salt1 tablespoon olive oil (plus extra for the bowl)3 cups unbleached white flour (1/4 cup may be whole wheat or rye)Extra flour for kneadingCornmeal for the baking trayPizza toppings3 thin slices fresh mozzarella (about 1 ounce)3 thin slices red onions (about 1 tablespoon)2 tablespoons thinly sliced mushrooms4-5 thinly sliced red, green or yellow bell peppers3 small broccoli or cauliflower florets#188; cup chopped artichoke hearts, drained well1 tablespoon sliced olives (any kind)#188; thinly sliced Roma tomato2 teaspoons grated parmesan cheese1 tablespoon chopped walnuts$CLASS=Recipedirections$Place the water in a medium-large bowl, sprinkle in the yeast and sugar, and stir to dissolve. Let stand 5 minutes, or until it begins to bubble.Stir in the salt, oil and 1 cup flour. Beat several minutes with a wooden spoon. Add the remaining flour 1/2 cup at a time, mixing after each addition. The dough will be soft, but should not be sticky.Turn the dough out onto a floured surface, and knead for several minutes. Place in an oiled bowl, cover with plastic wrap, and let the dough rise until doubled in bulk, about one hour.Punch down the dough, and return it to a floured surface. (This is the point at which you can freeze the dough for future use.) Divide the dough into four equal parts, knead each quarter for a few minutes, and then let the balls of dough rest 10 minutes. (This allows the gluten to relax, so the dough will stretch easily into shape.)Patiently stretch each ball into a 6-inch circle. Sprinkle two baking trays with cornmeal, and place two circles on each. (Meanwhile, heat the oven to 500 degrees.) Top each pizza with any combination of toppings. Make sure that the walnuts are on top so they can toast.Bake in the lower half of the oven 10-12 minutes, or until the edges are crispy and brown. (If you're not sure it's baked through, take one pizza out of oven and cut it in half. If it is still a little doughy on the inside, return it to the baking pan and bake a few minutes longer.) Serve hot, warm or at room temperature.Makes 4 pizzas, 1 serving eachCook's note: One batch of dough divides perfectly into two, 1-pound ricotta-cheese containers - or fit a whole batch into a 1-quart yogurt container - for easy freezing. Take the container out of the freezer before you go to work, and it will be ready to roll, so to speak, when you get home.Prepare the topping ingredients while the dough rises.You can make several different pizzas and serve them together.@Recipe nutrition:Nutrition values per serving: 575 calories, 17 g fat (7 g saturated), 83 g carbohydrates, 5.5 g fiber, 21 g protein, 25 mg cholesterol 596.5 mg sodium.Adapted slightly from the California Walnut Commission