- Add oil to a frying pan and warm over medium high heat. Stir in onions and carrots and sauté until vegetables have softened, about 5 minutes. Add garlic and continue to sauté for another minute.
- Transfer onion mixture to a five or six litre slow cooker along with stock, lentils, corn, cumin, curry and turmeric, if using. Cover and cook on high for two to three hours, or on low for five to six hours, until lentils are completely tender.
- Using either a hand blender or a blender, puree soup to desired consistency. In a blender you will need to puree the soup in batches. Return soup to slow cooker and stir in half a lemon’s worth of zest, one whole lemon’s worth of juice, salt and pepper.
- Serve warm. Soup may be made ahead and refrigerated in an airtight container for up to three days or frozen for up to three months.
Tip: To add an extra kick of protein place a chicken breast or two into slow cooker along with other ingredients and cook as directed. Remove chicken breast before pureeing soup, shred using a couple of forks and stir back into finished soup.