Equipment
Ingredients
Aromatics and Base
- 15 ml olive oil
- 1 yellow onion, diced
- 3 garlic, minced
- 15 g fresh ginger, peeled and finely grated
Spices
- 4 g ground cumin
- 3 g ground coriander
- 2 g ground turmeric
- 1 g red chilli flakes
Bulk Ingredients
- 500 g sweet potato, peeled and cut into 2cm cubes
- 150 g red split lentils, rinsed thoroughly in cold water and drained
- 1000 ml vegetable stock, hot
Finishing
- salt
- black pepper
- 15 ml lemon juice, freshly squeezed
Nutrition (per serving)
Method
Heat the olive oil in a large saucepan or Dutch oven over a medium heat until shimmering.
Add the diced onion to the pan and cook for 5 to 7 minutes, stirring occasionally, until softened and translucent.
Stir in the minced garlic, grated ginger, cumin, coriander, turmeric, and chilli flakes. Cook for 1 minute until highly fragrant.
Add the cubed sweet potato and rinsed red lentils to the pan, tossing them in the spiced onion mixture. Pour in the hot vegetable stock and bring the liquid to a rolling boil at 100 degrees Celsius or 212 degrees Fahrenheit.
Reduce the heat to medium-low, partially cover the pan with a lid, and allow the soup to bubble gently for 20 to 25 minutes.
Remove the pan from the heat. Carefully submerge the immersion blender into the liquid and process until completely smooth and velvety.
Taste the soup and stir in salt, freshly ground black pepper, and the fresh lemon juice if using. Ladle into warm bowls to serve.
Chef's Notes
- Always rinse red split lentils thoroughly under cold running water until the water runs clear. This removes natural saponins and dusty residue which can make the soup foam excessively or taste mildly bitter.
- Do not skip the step of blooming the spices in the hot oil. Fat-soluble flavor compounds in the cumin, coriander, and turmeric open up dramatically when toasted, resulting in a deeper, more complex final bowl.
- The squeeze of fresh lemon juice at the end is technically optional but highly recommended. Earthy ingredients like sweet potato and lentils can taste flat without a hit of acid to provide balance and high notes.
- This recipe benefits significantly from resting. Making it a day in advance allows the spices to meld and intensify. It will thicken in the fridge, so be prepared to loosen it with a splash of water upon reheating.
Storage
Refrigerator: 4 days — Store in an airtight container. The soup will thicken as it cools.
Freezer: 3 months — Leave 2cm of headspace in the container as the liquid will expand when frozen.
Reheating: Reheat gently in a saucepan over medium-low heat. Add a splash of water or vegetable stock to loosen the consistency if it has thickened during storage.
