Baked Fish Parcel with Butter Beans

Cooking in foil is one of the oldest tricks in the home cook's book. The fish steams in its own juices, the leeks go soft and sweet, and the whole thing lands on the plate in one piece with no pan to scrub afterwards. Baking en papillote, which is the French name for it, was once a way of keeping delicate food moist in ovens that ran hot and uneven. You get the same benefit at home with very little effort.

A word on the fish. Chunky white fillets such as cod, haddock or pollock hold together well in a parcel, and they stay flaky rather than dry because the foil traps the steam. Pull a piece from the thickest part of the fillet with a fork after about 12 minutes. If it's still glassy in the middle, give it a few more minutes and check again. Overcooked white fish turns chalky quite fast, so it's worth peeking early.

The leek is doing more work than it looks. Slice it thinly and rinse it well, because grit hides between the layers. Butter beans bring a soft, buttery texture that suits the crème fraîche sauce, and they make the supper filling without any fuss. If you like a little more brightness, a squeeze of lemon over the fish just before you eat it lifts everything.

If you have leftover fish, flake it cold into a lunch salad with a few leaves and some of the beans, or warm it gently with a spoonful of stock and eat it on toast. Leftover beans keep for a couple of days in a covered container in the fridge, and they're good mashed with a little garlic and spread on bread.

For something to serve alongside, a plate of peppery watercress and a few slices of rye or wholemeal bread make a good partner. If you want to build a bigger spread, the Herb Crusted Baked Cod Fillets follow the same comforting idea with a crisper top, and the Quick Thai green fish curry is a lovely midweek change when you want more warmth and spice. For a fish-and-greens night in a different direction, the Lemon Thyme Fish Parcels are a close cousin of this one.

Open the foil carefully, because the steam comes out hot. Eat it straight from the parcel if you like, with a spoon for the sauce, and don't worry about getting every last bean.