Mix the cold water and salt until the salt dissolves. Cut the salmon into large chunks. To clean the scallops, remove and discard the guts and the unwanted membrane, keeping only the white flesh and the roe sac. Add the salmon and scallops to the brine and leave it for about 20 minutes.
In the meantime, finely slice the spring onion and rinse the fresh herbs. Heat a frying pan on the grill or open fire. Remove the salmon and scallops from the brine and let them dry on a kitchen towel for a short while. Brown the butter until it is really golden and smells a bit nutty. Add a few splashes of the 12% distilled vinegar to the frying pan to break up the fat.
Place the salmon and scallops on a large platter and garnish with fresh herbs and spring onion. Serve with brown butter and freshly ground black pepper.