Remove the stalks of the fennel and slice off the hard bottom, discard stalks and bottom. Slice across the bulb to make thin semi-circles. Sweat the onion and fennel in a good dollop of oil over medium-low heat for 5 minutes. Add garlic and continue sweating for another few minutes.
Add broth, thyme, some salt and pepper then bring to a boil. Lower heat and simmer for 10 minutes.
Add potatoes and simmer for 20 minutes until potatoes are soft.
Blend soup until smooth with a blender or hand blender. Season with salt and pepper to taste, then stir in soymilk for added creaminess.
Variations:1) For a creamier, thicker soup, sprinkle fennel, onion and garlic with 2 tablespoon flour near the end of sweating. Stir well to coat before adding broth.2) For a greener soup, add half a cup of frozen peas with potatoes.3) For a brighter fennel taste, add 1/2 teaspoon fennel seeds with the thyme.