Toss with salt, pepper, and enough olive oil to generously coat – about 3-4 tablespoons. Move to the oven and roast for about 30 minutes, tossing occasionally, until veggies are tender.
Increase heat to 475 and roast for another 10-15 minutes, until everything is deeply caramelized. Remove from the oven and reserve a few small crispy cauliflower + mushroom bits to garnish.
Add the entire contents of the roasting tray to a large soup pot along with the remaining broth, raw cashews, nutritional yeast, coconut aminos or tamari, and balsamic vinegar.