Bowl of soup with jar of lentils, leek, sweet potato and garlic behind.

Oh So Simple Leek and Sweet Potato Soup!

When the weather gets chilly, I love to warm myself from the inside with this oh so simple leek and sweet potato soup!

Leek and potato soup is a classic favourite, but this versions has a little twist with the addition of sweet potato and red lentils, increasing the nutritional content of this already healthy bowl of goodness.

The goodies

Leeks come from the same family as onions and garlic, and all three are prebiotics, meaning that they feed the healthy bacteria in your gut. The microbiome consists of both helpful and potentially harmful bacteria. We are just beginning to understand quite how important our microbiome is, influencing gut health, weight, immune system and mental health. The key to a healthy gut microbiome is to create and maintain the right balance of bacteria, as an imbalance can make the body more susceptible to disease. So we want to feed the good guys!

Sweet potato is high in soluble and insoluble fibre particularly with the skin left on. They keep you full for longer, help to balance blood sugar and improve gut health. Sweet potato is an excellent source of beta carotene, which the body converts to vitamin A, along with good levels of vitamin C and potassium. They are an antioxidant food and even contain a small amount of protein.

Red lentils are high fibre and an excellent source of protein making this delicious soup a more complete meal. The protein slows down the release of carbohydrates from the potatoes and sweet potatoes, so will keep you feeling sustained for longer. Red lentils contain B vitamins, iron, magnesium, potassium and zinc. They also contain anti-inflammatory and antioxidant polyphenols.


Serves 4

  • 1 tbsp olive oil plus a dash of sesame oil
  • 2 medium leeks, sliced
  • 2 cloves of garlic crushed
  • 150g white potato cubed (leave some skin on white and sweet potato for added fibre and nutrients)
  • 250g sweet potato cubed
  • 1 cup of dried red lentils well rinsed
  • 1.5 litres of vegetable stock
  • 1 tsp of harissa (optional)


  • Heat the oil in a large saucepan, add the lentils, stirring for 2-3 minutes on a medium heat
  • Add the leeks and garlic, cover and turn the heat down for 5 minutes, stirring occasionally
  • Now add the chopped potato and sweet potato
  • Pour on the vegetable stock mixed with the harissa if using
  • Cook with the lid on for 15-20 minutes until soft
  • Season to taste
  • Roughly mash the soup with a potato masher to keep some texture

Serve with grated cheese or nutritional yeast flakes on top and enjoy!