Heat oil in a large pot over medium-high heat. Add onions, and cook, stirring occasionally, until translucent but not brown, about 15 minutes.
Stir in salt, stock, and water. Bring to a simmer, and cook for 15 minutes.
Remove from heat, and let cool for 20 minutes. Working in batches, puree in a blender, starting on low speed and gradually increasing to high, blending until soup is smooth.
Divide soup among 4 bowls, drizzle with oil, and serve with flatbread on the side.
I made this a couple years ago and loved it. I added a block of tofu for added protein and it blended just fine. I'm making it again this evening!
Didn't like this recipe very much. Very bland.