Trim the roots and dry tips form the spring onions. Finely slice them. Scrub the carrot and dice it (no need to peel). Trim the dry ends from the celery and finely slice it.
Warm a large pan over a medium heat for 2 mins, then add 1 tbsp oil and the chopped veg. Season with a pinch of salt and pepper. Gently fry for xx mins, stirring occasionally, till the veg have softened but not picked up too much colour. If they start to brown, turn the heat down.
While the veg fry, scrub the new potatoes and chop them into 3cm wide chunks. Peel and crush or grate the garlic. Crumble the stock cube into a heatproof jug and stir in xxml boiling water to dissolve it.
Stir the garlic and potatoes into the pan. our in the stock. Pop on a lid and bring to the boil. Once the soup is boiling, turn the heat down and simmer for xx mins, till the potatoes are tender.
While the soup simmers, roughly chop the wild garlic.
When the potatoes are tender, stir the garlic and mustard into the soup. taste, and add more salt or pepper if you think it needs it. Ladle the soup into warm bowls and serve.