The first step is to think about what's in season. Right now that means winter squash, root vegetables, mushrooms, broccoli, leafy greens, cauliflower (like my Curried Cauliflower Soup, above), and anything else that grabs you at the farmers' market. If you're a smart shopper some of these veg are already in your kitchen, right? Good answer!
Next, start with a dice of onion and celery. If you want, a bit of minced garlic, shallot, or a diced carrot go along way in adding flavor too. If you don't have them, no worries. Saute these aromatics in some olive oil and/or butter (with a pinch of salt) until they're tender. Now, pick your veg of choice and cut it into bite sized pieces. Remember, this soup will get pureed so perfect knife skills don't matter here but the more evenly sized the pieces are the more likely they'll cook at the same rate (plus, smaller pieces cook much faster). Saute the veg pieces with the aromatics for a few minutes then add your liquid. This can be stock (chicken, beef, veggie, or mushroom all work) or even water. Stock contributes great flavor while water lets the veg be the true star. A combination of both works too. Add enough liquid to submerge your veggies, bring the pot to a boil, then reduce the heat to a simmer and cook until the veggies are very tender. The time it takes depends on what you're cooking-squash will take a whole lot longer than mushrooms. Just taste them occasionally and you'll get there in 15-30 minutes. Once everything is very soft, puree the soup with an immersion blender or by transferring it (in batches) to a regular blender. Return the soup to the pot, taste it and season with salt and pepper (a squeeze of lemon is nice too). Occasionally it's too thick and needs a bit more liquid. If it isn't thick enough for you, continue to simmer it, reducing it down for a bit more depth. Another trick is to add a peeled, diced potato to the soup before pureeing-this gives it a lot more body and, in my opinion, a lovely, silky mouth feel at the end.
Once you have the technique down you can play with lots of flavors. Adding curry paste to the aromatics and using some coconut milk for the liquid creates a nice Thai influence. Miso and dashi go beautifully with mushrooms for a Japanese influenced soup. Chili flakes and anchovy paste punch up broccoli or broccoli rabe-drizzle with lemon juice and your favorite olive oil here too.
Because pureed soups are very smooth, I like to garnish them with something that adds a bit of texture-buttery toasted croutons, fried sage leaves, roasted nuts, or thin crisp breadsticks. Add a lightly dressed bowl of greens and dinner is done.
Would love to hear about your favorite veggie soup-what's cooking at your house?