Heat grill to high. Shuck corn and place directly on grill grates. Cook, turning occasionally, until charred. Remove corn from grill and set aside to cool.

Meanwhile, cook bacon in a large skillet over medium-low heat until crisp, 5 to 10 minutes. Transfer bacon to a paper towel–lined plate and drain.

Pour off all but 2 tablespoons of the bacon fat. Increase heat to medium-high and add potatoes. Cook undisturbed until potatoes start to brown, 3 to 6 minutes. Stir and cook 2 additional minutes. Add red pepper and cook, stirring occasionally, until potatoes and pepper are tender, 5 to 8 minutes. Transfer mixture to a medium bowl.

While vegetables are cooking, add sour cream, dill, and garlic to a small bowl and stir to combine. Season with salt and pepper and set aside.

Once corn is cool, cut kernels from cob and add to the bowl with the potatoes, pepper, and vinegar. Mix to combine. Season with salt and pepper.

Heat grill to medium-low. Turn dough out onto a floured surface and divide into 4 pieces. Roll each piece into a 7-inch-long oval and brush both sides with olive oil. Place flatbreads directly on grill grates and cover grill. Cook, checking every 2 minutes, until dough bubbles and stiffens and flatbreads have visible grill marks on the bottom, about 4 minutes. Flip flatbreads, cover grill, and cook 1 minute. Remove from grill.

Sprinkle each flatbread with ⅛ of the fontina and top with vegetable mixture. Divide remaining fontina equally among the flatbreads. Return flatbreads to grill, cover, and cook, checking every 2 minutes, until cheese is melted and dough is fully cooked, 3 to 4 minutes. Remove from grill. Using a pastry bag or a plastic bag with the corner snipped off, pipe ribbons of the dill-sour cream mixture across each flatbread. Top with reserved bacon.