For the herring, bring the water, lime juice, white wine, peppercorns, bay leaves, white wine vinegar and salt to a slow boil in a pan. Turn down the heat to a gentle simmer, add the fish and poach for about 12 minutes, or until cooked through.
For the potato salad, cut the cooked potatoes in half and place into a large bowl.
In another bowl, combine the mayonnaise, dill, mustard, lemon juice, curry paste, salt and freshly ground black pepper. Add to the bowl with the potatoes and stir to coat.
Drain the fish, then place it on top of the potato salad. Garnish with more dill and lemon wedges.