How to Make It
In a large bowl, whisk the 3 cups of flour with the yeast and 2 teaspoons of salt. Stir in 1 cup of warm water and the 2 tablespoons of peanut oil. Using your hands, knead the dough until smooth, 2 minutes. Cover with plastic wrap and let stand in a warm place until doubled in size, about 1 hour.
Meanwhile, in a large bowl, toss the potatoes with the 2 tablespoons of vinegar and season with salt and pepper. Let stand for at least 30 minutes or up to 1 hour. Drain.
In a large nonstick skillet, cook the bacon over moderate heat until golden and crisp, about 12 minutes. Transfer to a paper towel–lined plate.
Set a pizza stone on the bottom of the oven; preheat the oven to 500°. Lightly flour 2 large rimless baking sheets. Divide the dough into 2 pieces. On a lightly floured work surface, roll out 1 piece to a 14-inch round, 1/8 inch thick. Transfer to one of the baking sheets; keep the other piece covered with plastic wrap.
In a small bowl, stir the cheese into the crème fraîche. Spread half of the mixture over the pizza round. Top with half each of the potato and onion slices. Drizzle lightly with peanut oil. Cover with plastic wrap and let rest for 15 minutes. Repeat with the second piece of dough and the remaining toppings.
Carefully slide 1 tarte onto the hot pizza stone and bake for 12 to 15 minutes, until bubbling and golden in s. Transfer to a large board, top with half of the bacon and season with salt and pepper. Repeat with the second tarte and the remaining bacon. Cut the tartes into wedges, drizzle with malt vinegar and serve.