Wash herbs, shake dry and chop. 2⁄3 of herbs mixed with sour cream. Season with salt and pepper. Peel onions and cut into fine strips. Drain tuna, olives and peppers. Pluck the tuna, chop the olives and cut the bell peppers into strips.
Preheat oven (electric cooker: 220 °C/circulating air: 200 °C/gas: see manufacturer). Line a tray with baking paper. Place the tarte flambée bases on top and spread with herb cream. Spread tuna, onions, olives and peppers on top. Bake in a hot oven for 10-12 minutes. Sprinkle with the rest of the herbs.