Put the onion and potato in a large saucepan, along with the stock cubes, dissolved in 1.1 litres of boiling water. Bring to the boil, then reduce the heat and simmer for about 10 minutes, stirring occasionally.
Reserving a few mint leaves for the garnish, add the rest to the pan along with the frozen peas. Bring to the boil, then reduce the heat and simmer for 5 minutes.
Leave the soup to cool slightly, then transfer to a food processor or blender and blend until smooth.
Return the blended soup to the pan to heat through. Divide between 4 serving bowls and serve garnished with a swirl of yogurt and the reserved finely chopped mint.
Freezing and defrosting guidelines
Make the soup, then leave to cool at room temperature. Freeze (without garnishes or toppings) in a rigid container, leaving a bit of space for expansion, for up to 1-3 months. Reheat either from frozen or defrost in the fridge overnight. Once piping hot, add toppings or garnishes and serve.
See more Soup recipes