In a large pot or dutch oven, add the olive oil and diced onion. Saute over medium heat until it starts to brown, about 5-10 minutes.
Add in the minced garlic and diced celery stalk. Saute an additional 5-10 minutes.
Add in all remaining ingredients aside from the lemon and cover.
Simmer for 5-7 minutes or until the broccoli is fork tender. Start with just 1/2 tsp of salt and add more later as desired.
Transfer to a blender and blend until smooth.
It helps to start the blender on the lowest possible setting and keep the lid slightly ajar so heat can escape.
Add in the lemon juice and blend again.
Taste and adjust flavors as desired. I usually add a bit more pepper and lemon juice, but more salt or nutritional yeast is also delicious!
The soup will have a fairly thick consistency at this point, but if you want to thin it out, just add more vegetable broth, about 1/4 cup at a time, until it reaches your desired consistency.
Transfer back to the pot and serve warm with cashew cream, a drizzle of olive oil and fresh (gluten free) bread!