Take the dough out of the refrigerator and let it rest at room temperature for about 10 minutes. Preheat the oven (electric cooker: 250 °C/circulating air: 225 °C/gas: see manufacturer).
For the cream mix sour cream and Harissa. Season to taste with salt. Peel onions and cut into strips. Peel and wash sweet potatoes and slice or cut them very thinly.
Unroll the dough and place it on a baking tray with the baking paper. Spread with harissa cream and cover with sweet potatoes and onions.
Bake in a hot oven for 10-12 minutes. In the meantime wash parsley, shake dry, pluck leaves from the stalks and chop coarsely. Sprinkle tarte flambée with parsley.