Place the fish fillets into a ceramic dish and pour over 2 tbsp of the Bitton Gourmet Rosemary Thyme Vanilla Oil and season with sea salt and freshly ground black pepper. Cover and place in the refrigerator for 2 hours.
Place a large saucepan (with a steamer) of boiling salted water over a high heat and bring to the boil. Place the potatoes into the steamer and over the boiling water and cook for approximately 10 - 15 minutes or until just tender. Remove the potatoes from the heat and allow to cool to room temperature. Slice thickly and set aside until required.
Place the long green shallots, parsley, olives, watercress and potato slices into a large mixing bowl and gently combine.
Remove the fish from the fridge ½ an hour prior to cooking and dust lightly with the flour.
Place a large non-stick frying pan over a medium heat and add 1 tbsp Rosemary Thyme and Vanilla Oil and 1 tbsp butter. When the oil is hot, place 2 fillets into the frying pan and cook for 2 to 3 minutes. Turn the fillets over and cook for a further 2 - 3 minutes or until just cooked. Remove from the pan and repeat with the last 2 fillets.
To serve, place a large spoonful of the potato mixture into the centre of each plate. Place a fillet on top and drizzle with a little extra Rosemary Thyme and Vanilla Oil.