In a heavy-based pot, heat the olive oil on a low to medium heat. Add the sliced leeks and cook for 5 minutes or until soft.
Add the fresh corn kernels and the salt and cook for around 5 minutes. Add the stock and bring the soup to a simmer for 15 minutes.
Remove from heat. When safe to handle, remove 2 ladles of the corn and pulse briefly in a food processor or blender. Return the pulsed corn to the soup.
Add the finely sliced spring onions and return to a low heat for 2 minutes.
Serve with a good crack of black pepper