- 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 5L or 6L slow cooker along with stock, lentils, corn, cumin, curry and turmeric, if using. Cover and cook on high for 2 to 3 hours, or on low for 5 to 6 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 3 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.