Preheat oven to 425°F. Lightly dust two baking sheets with flour.
On a floured surface, divide dough into two balls. Roll or stretch each into a 12x6-inch rectangle, then place on the prepared sheets.
In a small bowl, mix sour cream, mayo, garlic, lime juice, chili powder, and salt. Set aside 1/4 cup of this sauce for drizzling later.
Spread the remaining sauce evenly over both flatbreads. Top with corn, mozzarella, cotija, and a pinch of chili powder.
Bake for 15–20 minutes, swapping the sheets halfway through, until the crust is golden and the cheese is bubbly.
Drizzle with the reserved sauce, sprinkle with cilantro and extra cotija (if desired), and squeeze fresh lime juice on top. Serve warm.