For the dough, in a large mixing bowl of an electric mixer, combine the flour, sugar, salt, coriander and yeast. While running on low, slowly stream in the water. Mix with the dough hook until it comes together and forms a ball. Knead on high for about 5 minutes until soft and elastic. If dough is really sticky, add anywhere between a 1/4 cup to 1/2 cup more flour. It should be soft and only slightly sticky.
Transfer to an oiled bowl, turning over to coat both sides. Cover loosely with plastic wrap and a damp kitchen towel and let rest in a warm spot for about 1 hour or until doubled in size.
Preheat an outdoor grill or stove top grill pan over medium-high.
Coat the corn with 2 tablespoons olive and season with salt, pepper, and cayenne. Grill the corn until charred all around, about 15 to 20 minutes, making sure to turn every 5 minutes. Remove from grill and let cool on a plate or platter. Cut the kernels off the cob and set aside.
In a large bowl, combine the crema, mayo, cilantro, 1/4 cup cotija, coriander, a pinch of salt and pepper, and juice of half a lime. Stir until evenly combined.
Divide the flatbread dough in half and roll each half into a thin long rectangle. Brush the tops with the remaining tablespoon of olive oil. Place on the hot grill, oil side down, and cook on each side until golden brown and crispy, about 10 to 15 minutes.
Transfer the frilled flatbread onto a baking sheet. Spread liberally with the sauce and then cover the top completely with the grilled corn kernels. Sprinkle with remaining 1/4 cup cotija cheese, drizzle with a bit more crema (or leftover sauce) and garnish with cilantro. Cut and serve immediately. Enjoy!