1. Heat the oven to 425°. Oil two 12-inch pizza pans or large baking sheets. Press the pizza dough into an approximately 12-inch round, or 9-by-13-inch rectangle, on each prepared pan. Bake until the dough begins to brown, about 10 minutes.
2. Meanwhile, line a strainer with several paper towels. Put the drained clams in the strainer and press gently to remove excess moisture.
3. Spread the clams on the partially baked pizza crusts, sprinkle with the garlic, red-pepper flakes, and 1/4 teaspoon of the salt, and drizzle with 3 tablespoons of the oil. Bake the pizzas for 8 to 10 minutes. Do not overcook or the clams will toughen.
4. Meanwhile, in a large bowl, toss the greens with the cherry tomatoes, the remaining 1 tablespoon oil, the vinegar, the remaining 1/4 teaspoon salt, and the black pepper. Remove the pizzas from the oven and top with the salad.
Plenty of Dough: If you're unable to find pizza dough in the refrigerator section of your supermarket, pizza places will often sell it to you by the pound. Just ask.
Wine Recommendation: Pinot grigio outsells other white wines in Italian restaurants by more than two to one, and this is the kind of dish that really shows why. Crisp, clean, and light, a good pinot grigio will nicely highlight the clams and tomatoes.