1. Dough: Stir together flour, salt, yeast, and 1 1/4 cups water in a large bowl until dough is very sticky. Cover with plastic wrap; let stand 12 to 18 hours at room temperature.

2. Sprinkle dough with flour. Divide in half. Divide oil between two 10-inch ovenproof nonstick skillets (preferably cast iron). Swirl to coat. Add dough to each skillet; turn to coat with oil. Gently flatten dough with your hand. Cover; let rise in a warm spot until doubled in bulk, about 2 hours.

3. Sauce: Meanwhile, heat oil in a medium pot over medium heat. Add pepper flakes and onion. Cook, stirring, until onion is tender, 6 to 8 minutes. Add tomatoes and juices. Bring to a boil, then reduce heat and simmer, stirring occasionally, until slightly reduced, about 20 minutes. Let cool slightly. Puree sauce in a blender, in batches (to avoid filling jar more than halfway), until smooth. Season with salt and pepper.

4. Toppings: Meanwhile, preheat oven to 400 degrees. Place eggplant in a colander; season with salt. Let stand 30 minutes.

5. Rinse eggplant, drain, and pat dry. Arrange on a baking sheet; brush with 2 tablespoons oil. Roast, turning once, until very tender, about 25 minutes. Let cool slightly, then cut into 1/2-inch pieces.

6. Heat remaining 1 tablespoon oil in a large skillet over medium heat. Add garlic; cook, stirring, until fragrant, 30 seconds. Add chard in batches with 1 to 2 tablespoons water. Cook, stirring, until just wilted, about 5 minutes. Season with salt. Let cool.

7. Preheat oven to 475 degrees with rack in lower third. For each pizza, press dough until it touches edge of skillet. Ladle 3/4 cup sauce over dough, leaving a 1/2-inch border. Top with 3 ounces cheese. Add 1/2 cup each chard and eggplant. Top with another 3 ounces cheese. Bake until crust is golden brown and cheese is melted, about 18 minutes. Sprinkle with oregano; serve.