Method
Prep:40min  ›  Cook:35min  ›  Ready in:1hr15min 

1. Preheat the oven to 200°C/gas 6. Put the salmon fillet in a shallow pan in which it fits snugly and add the stock, the stems from the dill (reserve the fronds for the sauce), the peppercorns and lemon juice. Bring to the boil, then simmer gently for 8–10 minutes until barely cooked. Remove the fish from the stock and, when cool enough to handle, break up into coarse flakes. Strain the stock and discard the flavourings. Set aside.
2. Steam the trimmed asparagus for about 3 minutes until barely tender. Cut off and reserve the tips, then chop the stalks into short pieces.
3. To make the sauce, melt the butter in a medium saucepan and stir in the flour, then gradually stir in the reserved stock and the milk. Bring to the boil, stirring constantly, to make a smooth light sauce. Simmer for 1 minute, then remove from the heat. Add the lemon zest, the chopped dill, skimmed milk, crème fraîche and seasoning to taste. Stir in the salmon and chopped asparagus stalks.
4. Arrange 3 sheets of lasagne over the bottom of a greased lasagne dish or large shallow ovenproof dish, of about 1.5 litre capacity. Spoon over a third of the salmon mixture. Repeat the layers twice more, then cover with the remaining lasagne sheets. Top with the reserved asparagus tips and press down gently all over, so the sauce comes up to moisten the top layer of lasagne.
5. Cover the dish with greased foil or a lid, then bake for 30–35 minutes until bubbling. Uncover the dish, sprinkle with the Parmesan cheese and serve immediately.

variation

Use undyed smoked haddock instead of salmon and replace the asparagus with tiny broccoli florets (there is no need to cook them before layering up).