Clean and cut the leeks: Cut off the roots of the leeks. Cut the leeks lengthwise, fan them open under running water to dislodge any dirt or mud hiding inside.
Cook leeks in butter to soften: Melt butter on medium heat in a 3 to 4-quart thick-bottomed pot. Add the chopped leeks, stir to coat with the butter.
Simmer the soup: Add the broth, diced potatoes, bay leaf, marjoram, thyme, and a teaspoon of salt to the pot.
Puree the soup: Remove and discard the bay leaf and thyme sprig. Use an immersion blender or standing blender to blend about half of the soup if you want a chunky soup, or all of it if you would like your soup to be more smooth.
Season the soup: Add the parsley, and cook a few minutes more. Add a few dashes of Tabasco to taste
Serving Size 1 cup (227g)
* Percent Daily Values are based on a 2,000 calorie diet. Your daily value may be higher or lower depending on your calorie needs.