1.Place whole potatoes in medium saucepan, barely cover with cold water; cover pan, bring to the boil. Reduce heat, simmer, covered, about 20 minutes or until tender. Drain. When are cool enough to handle, peel potatoes. Grate coarsely into large bowl.
2.Stir onion, eggs and flour into potato; season.
3.Heat oil in large frying pan. Drop 2 tablespoons of mixture into pan, making each pancake about 5cm in diameter. Cook about 3 minutes each side or until pancakes are browned lightly. Drain on absorbent paper.
4.Meanwhile, combine crème fraîche, dill and juice in small bowl.
5.Place pancakes on serving plates; top with salmon, dill cream, watercress and salmon roe. Sprinkle with a little extra dill.