Use a mandoline to thinly slice the potatoes. If you do not have a mandoline, this is still possible to do, but will take some extra time.
Add the eggs, coconut milk, sea salt and pepper, and herbs to a mixing bowl, and mix well.
In a 10-inch cast iron pan, use olive oil and coat the entire thing, including up the edges of the pan.
Lay the potatoes out, fully covering the bottom of the pan and up around the edges. With 3 potatoes, I needed 3-4 layers of potatoes across the whole pan.
When half of the potatoes are arranged on the pan, turn the stove on to medium heat. This will allow the potatoes to begin cooking as you finish arranging them.
Add the egg mixture to the pan with the potato crust.
Preheat the oven to 400°F.
Allow the eggs to begin cooking in the pan as the potatoes start crisping up. If the potatoes seem to be browning too quickly, reduce the heat. When you can see that about 1/2 the egg mixture has cooked, add the smoked salmon and asparagus to the top of the frittata.
Move the frittata to the oven to finish baking. Allow to bake for 15-20 minutes, until the eggs have set in the middle.
Serve immediately to enjoy the crispy potato crust! This is delicious served cold the next day, but the potatoes do not stay crispy once cooled.