Whisk together the water, oil and salt in a bowl. Add flour, stir in and mix until obtaining a smooth dough. Form it into a ball and let rest for 20 minutes at room temperature, wrapped in plastic foil. Preheat oven to highest setting.
Peel onion, cut into thin rings (about 2 mm) and season with 2 g salt.
Mix sour cream with a pinch of salt and some pepper. Cut bacon into strips, "Dolomit" cheese into slices (about 2 mm).
Lightly squeeze onion rings and remove excess water.
Depending on the desired size, cut the dough in half (200 g) or in thirds (130 g) and roll out as thinly as possible. If necessary, use a little flour. The ideal dough thickness is 1-2 mm, the classic shape is oval.
Spread a thin layer of sour cream on the rolled-out doughs and top with strips of bacon, slices of “Dolomit” cheese and onion rings.
Bake the Flammkuchen in a preheated oven at 250°C on the lowest rack for 6-7 minutes.
Once the edges are golden brown and the cheese has melted, remove from the oven, garnish with chives and some pepper and serve hot.