Roasted Sweet Potato Soup
This soup is layered with rich flavors, many of which are inspired by Thai cuisine (so don’t skip the fish sauce, coconut milk, and kaffir lime leaf, please, as they make the soup what it is). The sweet potato and carrots are roasted to develop a richer flavor, that mixes wonderfully with the brightness of lime and the savoriness of fish sauce, soy sauce, and Parmesan cheese. The Thai chilis will be very spicy if you’re not acclimated to them, so cook with caution. If you don’t have some of the ingredients on hand, don’t sweat it! You can make easy substitutions and omit some ingredients if needed—swap leeks for yellow onion, use all garlic if you don’t have shallots or vice versa, jalapeño or Serrano for Thai chilis, and even lemon juice instead of lime!
TIP: If you’re short on time, skip roasting the vegetables and simply finely dice the sweet potato and carrots, and simmer in the broth and coconut milk to soften them before pureeing. Or you can roast the vegetables a few days before.
Ingredients
- 6 ½ Tbsp avocado oil, or other neutral oil, divided
- 4-5 .75-1 lb large carrots, peeled
- 2 lb whole sweet potatoes, scrubbed and dried
- 4 large leeks, chopped
- 4 medium shallots, minced
- 6 cloves garlic, minced
- 1 ¼ tsp ground turmeric
- 1 Tbsp + 1 tsp ground coriander
- 2 Tbsp fish sauce
- 1 Tbsp dark soy sauce, or 2 Tbsp light soy sauce
- 4 cups vegetable stock
- 2 14 oz cans full fat coconut milk
- Zest of 2 limes
- 1 kaffir lime leaf, or ¾ tsp dried
- ¼ c lime juice, plus more to serve
- Salt to taste
- Cilantro
- Fresh or pickled Thai, jalapeno, or Serrano chiles (optional)
- Parmesan cheese, shaven or crumbles
Instructions
- Roast the sweet potatoes and carrots: Preheat oven to 400 degrees. Using a fork, prick the surface of the potatoes. Place the sweet potatoes whole onto a parchment-lined baking sheet and roast for 1-1 hour 30 minutes (depending on thickness of potatoes), until potatoes are tender and oozing sugar. When potatoes are done, turn off heat and allow them to rest in the oven overnight. You can also roast the potatoes in smaller cubes if needed.
- In a large bowl, toss the carrots in 3 Tbsp of avocado oil and a generous seasoning of salt. Place onto a large, parchment-lined baking sheet, or divide onto 2 large baking sheets to provide enough space for proper roasting. Transfer carrots to the oven and roast for 25-35 minutes or until brown and fork tender.
- As the vegetables roast, add 3 1/2 Tbsp avocado oil to a large pot or Dutch oven. Heat over medium-high, then add the chopped leeks and minced shallots. Season with salt and reduce heat to medium. Cook, stirring occasionally until reduced and lightly browned—6-8 minutes—then add the garlic, turmeric, and coriander. Continue stirring until fragrant, 3-4 minutes, then add in the fish sauce, and soy sauce, cooking for 1 minute. Add the sweet potato, carrots, coconut milk, and vegetable stock. Simmer for 35-45 minutes. After about 20 minutes, add the lime leaf and let simmer until ready to puree. Remove the kaffir lime leaf and transfer to a blender or food processor. Puree until smooth—this may need to be done in two batches. Taste for salt, and adjust seasonings as needed. Transfer back to the pot and stir in the lime zest and juice.
- Serve warm with more fresh lime, cilantro, Thai chilis, and a generous sprinkle of Parmesan cheese.
Notes
Dried kaffir lime leaf can be ordered online if you can’t find it in store. If you do find them in store, you can freeze them and have kaffir lime leaves on hand to make this soup again, or use in other dishes.