roasted zucchini and red onion soup
Prep Time: 15 minutes
Cook Time: 1 hour 10 minutes
Keywords: soup/stew gluten-free low-carb zucchini onion summer
Ingredients (serves 8)
- 1 1/2 lb. (680 g) zucchini, cut in half lengthwise
- 10 oz. (285 g) torpedo onion or other fresh red onion, cut into 1/4-inch (6 mm) thick rounds
- Olive oil
- Fresh thyme leaves
- Half a leek, about 2 oz. (56 g): I like to use the medium green part of a leek for this
- One large or two small garlic cloves, thinly sliced
- A small potato, scrubbed well, halved and sliced
- A small piece of seaweed (optional, I used a 2-inch (5 cm) piece of dulse
- 3-4 cups (710-950 ml) homemade light chicken stock (or vegetable alternative)
- A generous squeeze of lemon juice
- Sea salt and freshly milled black pepper, to taste
- Kale blossoms (optional)
Preheat the oven to 400 F. Place the zucchini, cut side up, and the onion rounds on a baking sheet lined with a silicone baking mat. Spray some olive oil and distribute some thyme leaves on the surface. Put in the oven and check after 30 minutes to make sure the onion is not brurning. If not, put back in the oven for another 5 minutes or so. Let cool slightly, so you can handle the vegetables without worry. Cut the zucchini halves in 1-inch long pieces.
Warm up some olive oil in a soup pot. Wash carefully, halve and cut into thin half-moons the leek, then add to the hot oil, together with some more thyme leaves. Stir well to coat. After a few minutes, add the garlic and stir. After a couple more minutes, add the roasted vegetables, potato and seaweed. Stir well, then add the stock and enough water to just cover the vegetables.
Bring to a boil and simmer for 25 minutes (this time should be enough to cook the potato, but check by smashing it with a spoon on the side of the pot: cook a bit longer, if necessary). Remove from the heat and add the lemon juice. Purée using an immersion blender, if possible. If you use a food processor, purée in batches and use extreme care. Add more water, as needed, to make the soup reach the desired consistency. Adjust salt and pepper to taste.
Since I use an immersion blender to purée the soup soon after it is ready, by the time I finished seasoning it, it is still hot. At this point, I throw into it a big handful of kale blossoms and cover the pot. The residual heat in the soup is enough to soften the blossoms and by the time I reheat the soup to serve it, they are tender to perfection. Making the soup at least a few hours before you are planning to serve it will give it enough time to rest and ripen.
Don't worry if you don't have kale blossoms: simply top the soup with some toasted pumpkin seeds or add cooked grains to it to make it a bit more substantial.