Makes 4 to 6 appetizer portions
2 Tb Butter
4 cups Leeks (from about 2 pounds whole leeks), whites and pale greens only
1 pound Russet Potatoes, peeled and small diced
1 tsp Kosher Salt
1 cup Whole Milk
¼ cup Heavy Cream, chilled
2 cups or more Vegetable Stock, chilled, plus more if needed to thin the soup
2 Tb thinly sliced Chives or Chopped Parsley for garnish
Slice the leeks and wash very well to remove all dirt that can be trapped between the layers. Drain the leeks well to remove the excess water.
Heat a stockpot over medium heat and add the butter. Once the butter is melted add the leeks to the pot, stir well to coat them with the butter and then cover the pot with its lid. Sweat the leeks for 4 to 6 minutes until tender, be sure to keep the heat low enough to prevent any browning of the leeks. Add the potatoes, the salt and the 2 cups of milk to the pot. Recover the pot and simmer until the potatoes are falling apart tender, about 10 minutes. Transfer the soup to the container of a blender; puree soup to a silky smooth consistency. Transfer the soup to a clean bowl and whisk in the chilled cream and 2 cups of the chilled stock. If soup is too thick add more of the stock to make it a thick but pourable consistency. Season with more sea salt if needed and chill soup until ready to serve.
Pour soup into serving bowls and garnish with the fresh herbs.