Ingredients
Method
1.Pre-heat the oven to 200°C. Lay the pastry out to fit a 30cm x 40cm oven tray. Allow the pastry to rest in the refrigerator for at least 30 minutes if possible.
2.In a heavy-bottomed frying pan, heat the olive oil and butter and add the onions. Cook slowly over a gentle heat, stirring frequently, for about 20 minutes until the onions caramelise. Ladle the onions onto the pastry and spread out evenly, scattering the fennel seeds over. Place in the oven and raise the temperature to 210°C. Bake for 15-20 minutes until the pastry is puffed and golden.
3.Meanwhile, stir the horseradish or wasabi into the crème fraîche and refrigerate until needed. When the tart is done, cover it with the salmon, drizzle the flavoured crème fraîche over, and top with the salmon caviar, some freshly ground black pepper and the herbs. Serve while warm.