We're big fans of roasting veg and immersion blending it. We tend to use enamelled cast-iron dutch ovens for the roasting, though, so if we're motivated enough to peel what doesn't have at least a nominally scoopable rind (when we're lazy, we halve, seed, and gut squash, then put onions and garlic to roast in the empty seed cavity; I guess that's our version of lazy), we are left with a nice one-pot meal that yields several days of lunches.
I sometimes like to make them like dilute curries, leaving texture to the blend, rather than blending and straining for a more refined presentation. We have yet to take any of our favourite indian dishes and make a soup inspired by it, but I could see saag paneer soup working very well (a spinach and unripened cheese dish), or lamb korma soup, for that matter. Or how about a butternut butter chicken soup?
Sorry, I have to stop. My drool is at risk of shorting my keyboard.
Okay, all better. But veg is really easy this way. It's like permaculture, or systems design. What functions are being filled by the veg in question? How is the spice palate being chosen to offset or otherwise complement them? If substitutions are made for individual variables, what will each change do to the taste, and what does that mean for the level of spice required, or the specific spice palate choice altogether?
And yes, as long as the relative densities aren't too dissimilar, I love how you can break it all down on a parchment papered sheetpan or into a dutch oven, roast until some elements are caramelised, and then blend it into deliciousness.
As to autumn produce, however, don't forget mushrooms. Some, like the chanterelle, whose flavours are most mobile in fats, are best soaked in cream of some kind which is then used in the soup along with the fresh or rehydrated mushrooms.
For a chanterelle and/or wild mushroom soup, I typically buy two pounds of whatever is available and will stand up well in a soup as texture and body. Creminis are great for this. If I am working with dried wild mushrooms or chanterelles, I rehydrate first, covering several times with just enough water, and using the last of the water, adding heavy cream to soak them in, sometimes with a good white wine, brandy, or cognac. If I am showcasing the mushrooms, I will go with a veggie broth. I have never done this with a mushroom broth, and I have also been meaning to try it with coconut cream, for a good vegan creme of wild mushroom.
And one observation I will leave from my much better half: you don't always have to blend them into oblivion. Also, sometimes, two soups with identical ingredients can present completely differently depending on what, if anything, is reserved for texural elements.
And from me, don't forget cheese. I love a good garlicky butternut soup with chicken or veggie broth and coconut cream, spiced with garam masala, cinnamon, turmeric, ginger, and just a touch of cayenne, pepper and salt to taste, but I generally only salt a little. Top that with a thin slice or three of brie, and you're golden.
For me, roasted veg soups were like when I discovered green smoothies, which I promptly turned black, with 5 oz of spinach and a cup of frozen blueberries in almond milk (I was unaware at the time of the environmental issues with almond agriculture, and my potential allergenic sensitivity to it); it was a new, easily adopted way to consume way more veg in a delicious way than I had known before. And for us, it also fits quite nicely with the "make big meals" approach to time-saving with food prep. We never lack for fast, delicious, and healthy lunches when we make soup. I literally salivate half the day until lunch in anticipation. I lose more keyboards that way.
Lovely ideas here, by the way. If one needs inspiration, one of my favourites is The Soup Bible by Debra Mayhew
. I think that's the one with the African Sweet Potato and Peanut Soup I love. Which reminds me, my addition to the flavourful mix-ins has got to be peanut butter, possibly with sriracha, if the context works. If my veg needs more roasty brownness than the veg provided, I like to use cocoa powder, sometimes a fattier red one mixed with a darker one. Unsweetened, no quik powder here, people.
But keep up the good replies. I love to discover new soups! Good luck, and keep us posted!