Preheat oven to 375°
Add cauliflower to a sheet pan and roast in the oven for 20 minutes until browned.
Remove from the oven and set aside.
Meanwhile, heat oil in a 4 qt soup or saucepan and saute onion for 5 minutes until golden.
Add garlic the last minute of cooking the onions, stirring the whole time. Season lightly with salt and pepper. p.s. don't burn or over-brown the garlic.
To the soup pan, add the roasted cauliflower, umami powder and crushed red pepper along with salt and pepper. Stir to incorporate for about 1 minute.
Add chicken broth, lemon zest and the 2 T of lemon juice.
Simmer over low heat for 10 minutes or so.
Remove from heat and pour the contents of the pan into a blender.
Put the lid on the blender and REMOVE MIDDLE INSERT OF THE LID leaving the hole open.
Place a folded dish towel over the blender hole opening to allow steam to escape.
Turn the blender on low and slowly ramp up to medium-high speed stopping the blender as needed to scrape the sides or push down the ingredients.
Blend for about 1-2 minutes until you can a super-smooth texture. Of course, if you like bits of cauliflower, stop the blender sooner.
Taste and correct for seasoning and/or texture by adding additional broth, if needed.
Pour into a serving tureen or bowls.