White fish baked in parcels with lemon, dill, courgette and capers, so it steams in its own juices and stays moist. Par-boil the potatoes and beans first; the fish only needs 12 to 15 minutes in the oven.

A serving has about 30g of protein for only 311 calories, including the potatoes and beans. White fish such as cod, haddock and pollock is one of the leanest protein sources there is, with less than 1g of fat per 100g.
Why parcels work. Sealing the fish in paper traps the steam from the lemon and courgette, so it cooks gently and stays moist with only a little oil. It is also very forgiving: the fish is hard to dry out, and there is almost no washing up.
Fish guidance. In the UK, the advice is at least two portions of fish a week, one of them oily. US guidelines suggest about 8oz (roughly 225g) of seafood a week for adults. White fish does not count as oily fish, so pair this with an oily fish meal such as the salmon traybake or the trout with almonds. Cod, haddock and pollock are all low in mercury.
Keep the potato skins on. New potatoes cooked in their skins keep more of their fibre. Capers add a salty, sharp flavour, so the dish needs only a little extra salt.
Not tagged for blood sugar, because the potatoes bring about 26g of carbohydrate a serving; swap half the potatoes for extra green beans if that matters to you. For another light fish dinner, see the sea bass with salsa verde.