For the tartare, place the pink sparkling wine in a pan, bring to the boil and cook to reduce the liquid to two-thirds of its original volume.
Mix the salmon, lime juice, avocado, dill, shallot, and reduced pink sparkling wine in a bowl. Season with salt and freshly ground black pepper.
For the dressing, combine the mayonnaise, tomato ketchup, brandy and Worcestershire sauce.
To serve, place a 7.5cm/3in chefs' ring in the centre of a serving plate. Spoon the tartare into the ring and press down well. Remove the chefs' ring. Place three prawns and three segments of grapefruit around the tartare and drizzle with the dressing. Repeat with the other plates and serve.
