1. Preheat oven to 475 degrees F. Using a tablespoon, scoop out zucchini centers to form "canoes," leaving a 1/4-inch border. Roughly chop centers; set aside.
2. Arrange zucchini, cut sides down, on a rimmed baking sheet; bake 15 minutes. Remove from oven.
3. Meanwhile, heat oil in a large skillet over medium. Add onion and 1/2 teaspoon pepper; cook, stirring, until soft, 3 to 5 minutes. Add chopped zucchini, and cook, stirring, until most of the liquid has evaporated, about 8 minutes. Remove from heat; let cool slightly. Fold in feta and tomatoes.
4. Turn hollowed-out zucchini cut sides up, fill with vegetable-feta mixture, and bake until top is lightly browned, about 20 minutes. Lift zucchini from baking sheet with a wide spatula, and serve.

Yield: 8 servings