When I had to go gluten-free and started reading labels, one of my favorite quick comfort foods was NOT gluten-free - cream of mushroom soup in the red and white can. For the past ten years I've mourned the loss until the other day when I found a recipe that, with a little tweaking, is the real thing. It can be used in place of canned soup in recipes too. And it's quick and easy.
2 Tbsp olive or other vegetable oil
Place 1 Tbsp. oil in a small pan or skillet on medium heat, and sauté onions until soft and transparent. Chop garlic and add, stirring. Onions could brown a little perhaps, but don't let the garlic brown. If needed, reduce heat so this doesn't happen.
While onions cook, in a blender (I use a Vitamix food processor) place the milks, cornstarch, and seasonings. (Note: if using sweetened almond or coconut milk, omit the sugar!) Process until mixed. Scoop the onion and garlic into the milk mixture, leaving behind some oil. Process again until smooth. Add the 2nd Tbsp. of oil to the pan. Chop the cleaned mushrooms (I like portabellas, but any kind will do) and add to the pan of oil and mushrooms. Sauté briefly stirring to coat with oil; they will soak it up . Add to blender and pulse just enough to chop mushrooms as fine as you prefer.
Pour into a large microwave-safe bowl and heat in 30 second increments, scraping and mixing with a spatula each time the microwave stops. Bring to a nearly full boil.
If you like a thinner soup, use only 2 Tbsp. cornstarch. For use in a casserole, as if right out of that famous red and white can, increase to 3 Tbsp. cornstarch. Serves one glutton (me) or two normal people.