Put the spring onions into a large pan with the potato, garlic and stock. Bring to the boil and then simmer for 12 - 15 minutes, until the potato is starting to soften. Add the peas to the soup base and simmer for 4 - 5 minutes.
Stir in the lemon juice and cool slightly. Remove 4 heaped tbsp of the potato and pea mixture to reserve for the garnish then blend the soup until smooth.
With the soup back in the saucepan, add most of the ham hock, reserving a little for the garnish. Heat the soup through, season with salt and pepper then stir in the crème fresh.
Serve the soup in bowls, garnished with the reserved peas, potatoes, ham hock and sprigs of mint.