Add olive oil to a large stainless steel (or other non-reactive) pot on the stove on medium heat.
Add onions to the pot when the oil is hot, and stir often for 4-5 minutes.
Add the celery, mix into the onions and stir occasionally for another few minutes.
Add ½ the garlic, and lower the heat a little.
Add the broth and combine with a quick stir
Add the main veggie to the pot, turn down the heat to simmer and add the lid to the pot.
Add some aromatic herbs if desired, now, or wait until later. Some folks like to season all the way along. ^^
After 15 minutes, remove the lid and use a fork to test the veggie for done-ness.
If the fork slides in/out easily, leave the lid off the pot and turn off the heat.
Remove the pot from the hot burner and use a hand-held (immersion)blender
to puree the contents of the pot. (if no immersion blender, see below)
After the soup has reached your desired consistency, (i.e. totally smooth or slightly chunky, your choice)
add the remaining garlic and your chosen aromatic herbs, other aromatic ingredients plus
sea salt/black pepper to taste. Just add a little at a time as we can adjust the salt level later.
The 'seasoning' step can be as simple as S & P with a smidge or two of hot pepper flakes or your favourite herb blend (e.g. Italian herbs, French "herbes de provence", curry powder etc) or more complex.
Place soup pot back on the heat and allow to simmer for another 10-20 minutes. This allows for these latest additions to mellow into the veggies. Taste again and adjust.