How to Make It
Preheat oven to 400°F with oven rack in top position. Stir together vinegar, oil, 1/4 teaspoon salt, and black pepper in a medium bowl. Stir in zucchini; let stand at room temperature 10 minutes.
Meanwhile, place pizza crust on a baking sheet; spread pesto over crust. Sprinkle cheese evenly over pesto, and top with tomatoes and crushed red pepper. Bake on top rack at 400°F until slightly crispy, about 6 minutes. Turn broiler to high, and broil until cheese is bubbly, 1 to 2 minutes. Remove from oven, and let cool 2 minutes.
Add baby spring mix, onion, and basil to zucchini mixture; toss to combine. Arrange salad mixture evenly over pizza. Sprinkle with remaining 1/4 teaspoon salt. Cut into 8 slices; serve immediately.