This month's edition of Bon Apetit had a fabulous recipe from Molly Wizenberg for Spicy Lentil Soup - to thicken the soup and make it creamy, it include a can of pureed chickpeas (with lemon juice and few tablespoons of olive oil, plus some garlic), stirred into the simmered French green lentils and vegetables. It made the soup delicious - creamy and thick, without being too rich or heavy.

A huge thank you to everyone for their advice, suggestions, comments to my dairy issue. As a big dairy fan, it is tough for me to think of dairy substitutions but with all of your help I now have many options to make 'creamy' soups. I can't wait to start cooking this weekend!

I use 1/3 cup of arborio rice. Just dump it in and let it cook with the soup and then when the soup is done , puree away, you'll never miss the cream.

Ditto the soy milk. Trader Joe's makes a soy creamer but the Earth Balance unsweetened soy milk is pretty rich tasting.

I use soy milk.

Along those lines, you could soak a hunk of day-old bread in water and incorporate it at the puree stage.

Just to add, a lot of gazpacho recipes I've seen use a small amount of fresh bread crumbs as a thickener. Didn't know about celeriac; want to try that one.

Along the lines of @usuba dashi's suggestion of celeriac, you could use kohlrabi, peeled, sliced and simmered along with your other ingredients. Its flavor is quite mild, subtly sweet, and it gives the silkiest of textures to a pureed soup.

Potato flour, rice flour, garbonzo bean flour are all great options.

I've used oatmeal. Depending on the texture of your soup, you may want to puree the oatmeal, but if it's a chunky, dark soup, it won't be noticeable if you skip that step. I think that it thickens it really well, withou dulling the flavor.

I've also had sucess using pureed rice.

I was going to say potatoes, and then I was going to say red lentils. Others beat me to it! Pureed white rice will also work, as will rice flour. I love foodpickle. So many great ideas.

Similar to bread crumbs, tortillas are great for thickening soups with Mexican flavors. To get the creamy flavor in soups with Indian or Thai flavors, I've used coconut milk with great results.

America's Test Kitchen (or maybe it was Cooks Country?) did a Creamy Tomato Soup on TV a couple weeks ago that was non dairy, It was thickened with bread crumbs of all things.. It looked so good I went to the website and got the recipe. (It' was a freebee recipe because it's this years show.) It was thick and creamy in appearance and there was not a lick of dairy in it. I was interested in the technique to use in other sauces as well.

The oldest trick in the book - celeriac (celery root). I learned this trick 30 years ago in Europe. You you be surprised how creamy the soap will taste.

healthierkitchen is right. Red lentils in particular make a great, hearty base that does not need extra thickeners (though I really like a big dollop of raita in those I make with curry spices). I make this, or some variation on it, about three times a month: http://www.food52.com/recipes/7020_red_lentil_and_cauliflower_soup Red lentils don't need any soaking, and generally cook up in the same time it takes to cook the aromatics and vegetables in the soup. ;o)

pureed soups with butternut squash and sweet potato will naturally thicken without cream. Likewise, lentil and pea soups. innoabrd's note about nuts reminded me of a delicious curry dish I had at an Indian restaurant last weekend - thickened with ground cashews.

Stale bread crumbs, like in a classic ribollita. http://www.epicurious.com/recipes/food/views/Ribollita-357309

I use coconut milk in some recipes- like butternut squash soup, sweet potato.

Potato flakes! So easy and they simply vanish. Also, the starch from cooked potatoes or noodles, in the cooking water, works really well, too. Get the sediment from the bottom of the pan. Freeze it in small ziplog bags or in ice cube trays. BTW< that potato water, and those potato flakes too, are my secret weapon in my homemade bread (Pullman loaves for sandwiches and toast, that is) ;o)

I'm all for the potatoes too, but ground nuts or nut butter, I'm thinking almonds in particular, might help give a thick texture and richness to the soup that some of the other substitutes might not.

I'm also wondering if any of the soy milks would work? I've never had, so don't know what happens when you cook them. Can they be reduced?

Oops...I must be a slow typist...sorry for the redundant spud advice!

If it's a pureed soup, like cream of broccoli or zucchini, etc. you can cook a potato in with the other veggies. It will thicken the soup when you puree it.

Or potatoes - boil them in there and then you can puree the whole thing or take out part and puree it and add it back in if you want to keep some chunks as well

If you're going to puree, then you can add 1-2 starchy diced potatoes to the soup you're cooking. The starch in the potato will thicken the soup when it's pureed. You can also make a roux or slurry with flour & water and add that to the soup slowly, stirring as you add.

potatoes also--just puree them and stir them in. If you can puree the entire soup, it will be creamier.

I've used pureed rice.