Made this following the recipe (except when I discovered I had no canola oil+used olive)+it's too watery. How can I thicken it upw/out yogurt? thx!

Another approach - instead of adding thickener, drain the soup and only add back part of the drained liquid...to desired thickness.

Short of roasting more cauliflower to blend into your soup, I don't think you'll thicken this soup without adding something along the lines of boulangere's suggestions. Sounds to me like the ratio of liquid to soup "filings" is just not what you were hoping for in this recipe.

My favorite way of thickening a soup without adding flour in any form is to grind a couple of tablespoons of white rice in my coffee grinder. First I grind a handful of oatmeal, which does an excellent job of scouring out coffee grounds and absorbing coffee oils, and discard it. Once I've ground the rice finely, about the same grind as espresso, I pour it into a bowl, then add a couple of ladles of soup, or whatever needs thickening, whisk it all together, then pour it into the soup in a gradual stream, stirring continuously. Keep stirring for a minute or so. You will feel the soup begin to thicken. The advantage of using rice is that you don't have a floury taste to deal with, nor the gluten question. Too, the rice granules will distribute evenly throughout the soup rather than sinking to the bottom and clumping.