Rinse, trim and slice the leek and the stick of celery. Peel and chop the sweet potatoes into roughly equal-sized chunks. Peel and grate or crush the garlic. Rinse and chop the parsley leaves and stalks.
Peel the skin off the salmon. Flake the salmon into good-sized pieces. Fill the kettle and boil it.
Warm a splash of olive oil in a pan. Add the leek, celery and garlic. Season with salt and pepper. Stir and fry for 5 mins over a medium heat till the veg is soft and glossy.
Add the sweet potatoes to the pan. Give everything a good stir. Pour in 600ml hot water from the kettle. Stir and cover.
Bring the chowder to the boil, then turn the heat down. Let it gently simmer for 10 mins till the potatoes are nice and soft.
Turn the heat right down to the lowest possible setting. Add the salmon. Pour in the milk. Give the chowder a stir. Let it warm through. Don’t let it simmer or boil. You just want to gently warm the milk and salmon.
Stir in most of the parsley. Taste. Adjust the seasoning if you think it needs it. Ladle into warm bowls. Top with the last of the parsley to serve.