Slimming World's chicken, tarragon and lemon soup

Ingredients

• 1 medium onion, finely chopped
• 600ml boiling chicken stock
• 1 tbsp Knorr Touch of Taste Chicken Concentrated Liquid Stock
• 1 large skinless and boneless chicken breast
• 1 medium floury potato, such as King Edward, peeled and cut into chunks
• Zest and juice of 1 small unwaxed lemon
• 4 tbsp chopped fresh tarragon, plus sprigs to garnish
• 4 tbsp fat-free natural Greek yogurt, plus 4 tsp to serve
• Leftovers can be stored in the fridge for 2 days. Reheat thoroughly before serving.

Method
Put the onion and 4 tbsp stock into a lidded saucepan over a medium-high heat. As soon as it is bubbling, season lightly, cover and reduce the heat to low. Cook for 10 minutes or until soft but not browned. Add the rest of the stock, concentrated stock, chicken and potato to the pan, cover again and cook gently for 20 minutes.
Lift the chicken on to a plate and, when it is cool enough to handle, gently shred the meat and keep warm. (The chicken pieces will give your soup a lovely texture.) Blitz the soup with a stick blender (or use a food processor or blender). Stir in the lemon zest, lemon juice, most of the tarragon, half of the cooked chicken and seasoning to taste. Bring back to a gentle simmer.
Remove the pan from the heat and stir in the yogurt. Ladle the soup into warmed bowls, swirl in the extra yogurt and scatter over the remaining tarragon. Pile the rest of the chicken in the middle of each bowl and garnish with tarragon sprigs to serve.