Zest one lemon and then juice the same lemon. Combine the zest and lemon juice with the crème fraiche, dill, and chives and mix well. Refrigerate until serving. Peel the sweet potato and russet potato and shred with a coarse grater or food processor with a medium grater attachment. Place in a bowl and add 1 teaspoon sea salt, toss and allow to stand for 10 minutes. Place potatoes in a strainer and rinse under cold water, drain and return to bowl. Add 2 whisked eggs along with the flour, ½ teaspoon salt and a pinch of ground pepper and mix well.
Place coconut oil (or canola oil) in a skillet or griddle pan and heat at medium high on the stove top until hot but not smoking. Spoon heaping tablespoons of the potato mixture into the hot oil and flatten with a spatula to make a 3 inch diameter cake. Fry, turning once so that both sides are golden. (The cakes can be kept warm for a short time in a 200 degree F oven until ready to serve).
To serve, arrange the pancakes on a warmed platter and top each cake with a piece of smoked salmon and a dollop of the herbed crème fraiche. Serve immediately. These pancakes are great on their own and can be an ideal side to any meal without the toppings!