Line a rimmed baking sheet with aluminum foil; preheat the broiler to high.
Trim the ends from the zucchini, and slice each zucchini crosswise into 24 1/2- to 3/4-inch rounds.
Heat the olive oil in a large nonstick skillet set over medium-high heat. Add the zucchini and cook on one side only, 4-5 minutes, until browned.
Transfer the zucchini to the baking sheet, browned side up. Top each round with 1/2 teaspoon of the pizza sauce, a pepperoni slice, and a piece of mozzarella.
Broil the zucchini until the cheese is melted, 4-5 minutes (watch the pizza bites closely, as broiler intensities vary).
Top with a slice of fresh tomato and chopped basil. Salt if needed. Serve!