No need to throw away the bony bits of crabs, crayfish or even prawns - with a little care they can be transformed into delicious sauces and dressings
I like to use every bit of an animal, a vegetable or a fish. The bones for soup, the pan juices for a sauce, the vegetable peelings in a stock. Even pastry trimmings will be baked to nibble at with a cup of coffee as soon as they come from the oven.
There is much flavour to be had from a crab shell too, or even that of a bag of prawns or crayfish. To consign them to the bin unused is as wasteful as throwing away the bones of the Sunday roast before you have used them for stock or gravy.
As you crack the claws of a crab and pull out the coral-flushed white meat, keep the empty claws and the body shell safe. You can smash them with a heavy weight, cover them in water, tuck in a bay leaf or two and a few parsley stalks and simmer for 20 minutes till you have a rose-pink stock. Use it as the base for a noodle soup or a sauce.
The shells and heads of a bag of prawns seem thin and light beside that of the lobster and the crab and are more likely to be tossed aside as useless. Yet bring them to the boil with a few aromatics and in 20 minutes or less you will have produced a delicate bouillon, mild and sweet - a good start for a mild broth of prawn, lemongrass and ginger. You can add greens such as pak choy or spinach and some long thin rice noodles, too. (A suggestion: cook the noodles separately to keep the fish broth clear and fresh tasting, then add them to the broth with shredded Chinese greens, grated ginger and chopped fresh mint leaves.)
The bisque of the classic French kitchen, made with lobster or crabmeat and crushed shells and thickened with stale breadcrumbs, is generally too rich for me, but it has its fans. Traditionally made by pounding the shells, claws and heads to a paste, this is the stuff of hard kitchen labour. But we can still make a sound stock for the home kitchen by smashing up the carapace and simmering it with water, thyme and a few aromatic bits and bobs.
This week I made a surprisingly deeply flavoured crab sauce by leaving the broken shells to infuse with warm cream and a couple of bay leaves. I bolstered the flavour with a few spoons of brown crabmeat and used it to dress a salad of white crab and asparagus. An occasional and rather special summer treat.
But you can get the best out of shellfish with even less fuss. This week we ate langoustines grilled with the shells rolled in butter and grated Parmesan. Once we had winkled out the meat, we had the shells, coated in toasted butter and Parmesan, to suck to our heart's content. Yes, we could have eaten only the plump snow-white flesh inside, but that would have meant missing a gloriously messy and rewarding bit of eating.
Asparagus with crab sauce
I like my asparagus to be cooked longer than most, until it bends. The flavour is better that way. That said, I cooked the spears lightly for this, keeping them quite crisp. Works nicely with the soft, sweet crabmeat.
crabshell and cracked claws
lemongrass a long plump stalk
garlic 2 cloves
ginger a large thumb
double cream 250ml
brown crabmeat 175g
asparagus spears 10
white crabmeat 150g
Smash the crab shell and claws into manageable pieces and put them in a medium-sized saucepan. Crush the lemongrass with a heavy weight so it splinters, then tuck it among the crab shells. Squash the garlic cloves and drop into the crab then peel the ginger, slice into thick coins and add both to the pan. Pour in the cream and bring to the boil, then turn off the heat and leave, covered, to infuse for about half an hour.
Warm the grill or griddle pan, lightly oil the asparagus spears, trimming the ends if necessary, then cook till they are lightly coloured and still (just) crisp. Sieve the crab sauce to remove the lemongrass, ginger, garlic and shells, then stir in the brown crabmeat and warm gently.
Divide the hot asparagus between two plates, add the white crabmeat, fresh and unseasoned, then spoon over the sieved crab sauce.
Grilled langoustines with Parmesan butter
Should you see them for sale, signal crayfish are also ideal for this recipe.
Parmesan 50g, grated
mild smoked paprika 2 tsp
chilli one medium-hot red
Put the butter in a mixing bowl. Grate the Parmesan into the bowl and mash most of it into the butter with the smoked paprika. Halve, seed and finely chop the red chilli, then stir into the butter.
Slice the langoustines in half lengthways and place them cosily, cut-side up, on a baking sheet. Spoon the butter generously over the surface of the langoustines. Preheat the oven grill.
Scatter the remaining Parmesan over the top of the langoustines, place them under the hot grill and let them cook for 5 or 6 minutes till the butter is melted, the langoustines are lightly cooked and the crust is sizzling and golden. Eat while they are hot (fingers rather than forks), sucking the buttery, salty shells as you go.
Email Nigel at email@example.com or visit theguardian.com/profile/nigelslater for all his recipes in one place. Follow Nigel on Twitter @NigelSlater
A word in your shell like: Nigel Slater's asparagus with crab sauce recipe. Photograph: Jonathan Lovekin for the Observer