Place a pizza stone in the oven and preheat to 500°F. OR preheat your pizza oven (here’s the pizza oven we use).
In a medium bowl, mix the refried black beans with a bit of water to thin the consistency so that it is easily spreadable. Mix with 1/2 teaspoon cumin, 1/4 teaspoon paprika, and 1/4 teaspoon cayenne.
When the oven is ready, dust a pizza peel with cornmeal or semolina flour. (If you don’t have a pizza peel, you can use a rimless baking sheet or the back of a rimmed baking sheet. But a pizza peel is well worth the investment!) Stretch the dough into a circle; see How to Stretch Pizza Dough for instructions. Then gently place the dough onto the pizza peel.
Quickly assemble the pizza. Spread the bean mixture in a thin layer over the dough, sprinkle on as much cheese as you like, and add the red onion, tomato, jalapeño, corn, and cilantro. Sprinkle with kosher salt (very important – this really brings out the flavors!).
Transfer the pizza to the pizza stone using the pizza peel, and bake until the cheese and crust are nicely browned, about 5 to 7 minutes. Repeat Steps 4 through 6 for the second pizza (if your stone isn’t big enough for two!). Chop the cilantro and add it as a garnish. Add sour cream and pickled onions, if desired.