Pita bread is a simple solution for a not-too-filling pizza crust. Advance planning is necessary to caramelize the onions, but assemble and broil the pizzas just before serving.
2 tablespoons olive oil, plus more for brushing
1 large sweet or yellow onion, halved vertically and each half cut lengthwise into 1/8-inch-wide strips
1 cup diced tart apple, such as Granny Smith
2 tablespoons balsamic vinegar
2 teaspoons sugar
Salt to taste
Freshly ground pepper to taste
One 6-inch plain pita bread round, sliced horizontally
1 cup coarsely shredded mozzarella cheese
¼ cup coarsely chopped toasted walnuts
Heat 2 tablespoons of the oil in a large nonstick skillet over medium heat. Add the onions; cover and cook, stirring occasionally, for about 5 minutes or until translucent. Reduce the heat to low; add the apple, vinegar, and sugar. Continue to cook, stirring occasionally, until the onions are very tender and nicely browned, about 15 minutes. Add salt and pepper to taste. Remove from the heat and set aside.
Just before serving the pizzas, preheat the broiler. Place the pita halves, rough-side up, on a baking sheet. Lightly brush with olive oil. Broil 4 to 5 inches from the heat source for about 1 minute or until lightly toasted.
To assemble the pizzas, spread the crusts with the shredded cheese and top with the onion mixture. Sprinkle with the walnuts. Broil for about 1 ½ to 2 minutes, or until the cheese is melted.
To serve, cut each pizza into 8 wedges and serve immediately.
The onion mixture can be cooked up to 1 day in advance; cover and refrigerate. Bring to room temperature before assembling the pizzas.
Substitute pear, such as red or green Bartlett or Bosc, for the apple. Sprinkle the pizzas with about 2 tablespoons minced oil-packed sun-dried tomatoes before broiling.