Adjust oven rack to 6 inches below heat source; heat broiler. Place the potatoes in a medium pot, cover with cold water, and bring to a boil. Add 1 teaspoon salt, reduce heat, and simmer until tender, about 15 minutes. Drain, run under cold water to cool, then cut into quarters. Meanwhile, in a large bowl, combine the crème fraîche or sour cream, 1 tablespoon of the lemon juice, 1 teaspoon salt, and 1/4 teaspoon pepper. Stir in the potatoes and fennel; set aside. Place the salmon on a parchment- or foil-lined baking sheet. In a small bowl, combine the mustard and the remaining lemon juice. Spread over the top of the salmon. Broil until the salmon is the same color throughout, 6 to 8 minutes, depending on the thickness. Divide the salmon and salad among individual plates and sprinkle with the dill. Upgrade: For a snappy, licoricey boost, reserve the feathery green fronds of the fennel and mix them with the dill before garnishing.
Fantastic dish. Very very easy and the flavors were amazing. I'll make this again