Dice the White Onion (1). Core and dice the Fennel Bulb (1). Slice Yukon Gold Potato (0.5 pound), Roughly chop the Garlic (3 clove). Remove the ends from the Asparagus (1.5 pound) and chop them up. Save the tips for garnish.
In a large heavy bottom pot, saute onion and fennel in Oil (2 tablespoon) over medium-high heat, for 2 minutes, stirring constantly.
Turn heat to medium and continue cooking until softened, about 5-6 minutes.
Add garlic and saute for a couple more minutes, until garlic becomes fragrant.
Add Vegetable Stock (6 cup) and sliced potatoes, and bring to a boil. Cover, simmer on low 15-20 minutes until potatoes cooked through and are fork tender.
Add asparagus, turn heat up and return to a boil, and cook for 2-3 minutes. Don’t over cook or you will loose the lovely color.
Remove from heat and let cool a bit. In batches (see warning above) blend soup until creamy and very very smooth, adding in Tarragon (1/4 cup) and Fresh Basil (1/2 cup).
Blend really well, so there are no specs of herbs but rather, let them tint the soup and make it very green. Whisk in Sour Cream (1/2 cup). Return to the stove and heat gently. Do not let this soup boil, it will turn the color.
As it is heating … add the Kosher Salt (3/4 teaspoon) and Ground White Pepper (1/4 teaspoon).
Place Fennel Leaves (2 cup) and Italian Flat-Leaf Parsley (1 cup) in a strainer, and dip in a large pot of salted boiling water for 30 seconds. Remove and immediately cool in an ice water bath, to shock.
Drain, and squeeze dry with kitchen towels or paper towels to remove as much water as possible. Place in a blender, with just enough Canola Oil (3/4 cup) to cover (or less is fine too).
Blend, adding a little more oil if necessary, to keep the blade turning. Keep in mind, the less oil you use, the more flavorful this will be. Blend for a full minute, until fairly smooth.
Let this sit in the fridge, as long as possible, preferably over night. Strain with a fine mesh strainer or cheese cloth. Pour into a squeeze bottle. This keeps for a week or two in the fridge, or can be frozen.
Garnish with blanched asparagus tips, sour cream and fennel oil. Enjoy!