Roasted Cauliflower and Garlic Soup with Caramelized Onions

for the broth (optional): 4 tablespoons olive oil 1 large red onion, quartered 4 carrots, washed, trimmed, and cut in half 6 stalks celery, trimmed and halved 1 bunch kale stems 1 bunch parsley stems 6 cloves garlic, smashed and peeled 4 tablespoons sea salt 20 peppercorns 4 bay leaves 4 quarts water, plus more as needed In a big stock pot, heat the olive oil over medium-high heat. Add the onion and sear. Next, add the carrots and celery and cook for a few minutes more. Add the stems, garlic, and spices. Pour on 4 quarts water. Bring to a boil, and then turn heat to a simmer. Cook, so broth is gently bubbling, for 3 – 5 hours. Strain, pour into jars, seal, and refrigerate. (Aimee from Simple Bites has some great tips for freezing stock and broth in glass here.) for the soup 1 large head cauliflower, cored and cut into 1/2 inch thick slices 1 head garlic, broken into cloves, ends trimmed and smashed, with the papery skin left on 3 tablespoons olive oil 2 tablespoons lemon zest 2 tablespoon sea salt 1 teaspoon ground black pepper 1 teaspoon ground cumin 1 teaspoon ground coriander 4 – 5 cups vegetable broth (see above) Preheat oven to 400 degrees F. Toss the cauliflower and garlic with the olive oil, zest, salt, and spices, and turn out onto a rimmed baking sheet. Roast for 25 minutes, or until the cauliflower is tender and the edges are lightly browned. When it’s cool enough to handle, peel the papery skin from the garlic. Using your blender of choice, puree the roasted vegetables with the broth until smooth. Check salt levels and adjust as needed. To serve, heat over medium-low heat, stirring often, for 20 minutes. for the topping 1 red onion, sliced thin 4 tablespoon olive oil, divided 1/2 teaspoon sea salt, plus a pinch 8 crimini mushrooms, stems removed and sliced 1/4 inch thick pinch of black pepper 3 tablespoons parsley, minced Heat a medium-sized skillet over medium-high heat. Add 3 tablespoons olive oil, and then the onion slices and sea salt. Cook for 5 minutes, stirring often. Turn heat to low and cook, stirring occasionally, for 2 1/2 hours. After 1 hour they’ll be sweet but limp; after 2, delicious; but after 2 1/2 hours will they be crisp and sweet and perfect. Remove to a bowl. Just before serving the soup, heat the remaining tablespoon of olive oil in the same skillet. Add the mushrooms, salt, and pepper, and cook for about 7 minutes, or until the mushrooms have given up their water and are crispy on the edges. Fold in the onions and parsley. Off the heat and set aside. Ladle the soup into bowls, add the topping, and drizzle with olive oil.