Heat olive oil in a 10-inch nonstick broiler-proof skillet over medium heat.
Add zucchini, bell pepper, onion, thyme, 1/4 teaspoon salt, 1/8 teaspoon black pepper, and garlic. Cover and cook 7 minutes or until vegetables are tender, stirring occasionally. Stir in tomato. Cook, uncovered, for 5 minutes or until liquid evaporates.
Combine eggs, remaining 1/4 teaspoon salt, and remaining 1/8 teaspoon black pepper in a medium bowl; stir with a whisk until frothy.
Pour egg mixture into pan over vegetables, stirring gently. Cover, reduce heat, and cook 15 minutes or until almost set in the center.
Preheat broiler.
Broil frittata 3 minutes or until set. Invert onto a serving platter; cut into 8 wedges.