Peel the artichokes with a potato peeler, then place immediately into a bowl of cold water with a squeeze of lemon juice (to prevent them turning brown). Heat a large saucepan and add the butter – as soon as it starts to foam, stir in the onions.
Reduce the heat and cook for 10 minutes until soft. While you’re waiting for the onions to soften, quickly grate or chop the artichokes. Add them to the onions, season well with black pepper and add the boiling water or vegetable stock. Bring back to the boil before reducing to a simmer and cook, covered, for 20 minutes or more until the artichoke is meltingly tender.
Pour into a liquidiser and add the smoked salmon. Liquidise until smooth, taste and check the seasoning – you may have to add a squeeze more lemon juice too. Serve immediately with a dollop of crème fraîche and a sprinkling of chives.