Lettuce soup

Lettuce soup - more delicious than it sounds.
This recipe is from the Thermomix Festive Flavour cookbook which was my first cooking class just before my thermomix was delivered.

Ingredients
500g water
1-2 tbsp veg stock concentrate
8-10 green butter lettuce leaves roughly chopped - it's the butter lettuce leaves that give the soup a real buttery flavour so not sure how well it would work with other lettuce leaves
1-2 spring onions or shallots
30g butter
1 large potato peeled and roughly chopped
salt and pepper
1MC cream or yoghurt
fresh mint to garnish

Method
1. Place 400g water, stock, lettuce, spring onions and butter in bowl and mix sp9 for 10seconds
2. Add potato and cook for 15 mins 100degrees sp2
3. Check potato, if cooked, add s&p, cream and remaining water adn puree for 30seconds slowly up to sp9