Leeks are available year-round but their peak season is in late winter and through spring. While they are plentiful and inexpensive, it’s a good time to venture beyond the potato-and-leek soup comfort zone and see how lush and sophisticated leeks can be when they’re dressed up with a little stock and cream before being pureed into an elegant, pale-green sauce. Whether as a meal for family or as a dressed-up dish for entertainers, this is a dinnertime winner with a touch of restaurant flair. The sauce can be made a day ahead: in fact, Lesley Russell says, the flavour is best if you make it ahead of time. Once that’s done, it’s a matter of minutes to blanch some spring greens and get the salmon ready to serve. Even easier, the pan in which you cook the salmon fillets can go straight from the stove to the table.