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Get cracking: yolks—the Midas touch

Categories: Expert guidance

In an ongoing series, cookery writer and Borough Market regular Jenny Chandler explores eggs in all their various forms. This week: sauces and emulsions

Words: Jenny Chandler  

Once in a while I feel obliged to make meringues, or even macarons if I have the time. I have an ever-expanding reservoir of egg whites in my freezer that need to be used (one white is 30 grams when thawed, so no is labelling required).

I’ve never had—and never will have—the weight watcher/weight lifter obsession with virtually fat-free, protein-rich albumen omelettes and fortifying drinks (that have reputedly led to egg white shortages in the US). Yes an egg white will give structure to a dish, but the yolk is where you find all the buttery sweetness and flavour.

Eating a boiled egg is all about getting through the subtly-flavoured white to the liquid gold within; the yolk is just perfect for dipping, a gloriously creamy readymade sauce requiring nothing more from the cook but a pinch of seasoning. Many indulgent dishes call for the yolk alone. Custards and quiches produce leftover whites, but the real causes of my gluts are yolky emulsions.

The fat is, the egg yolk is not only delicious (and packed with nutrients), it’s also one of the most efficient emulsifiers in the kitchen. Let’s begin with mayonnaise. The yolk is a complex emulsion of fat and water, packed with stabilising proteins such as lecithin, making it a fabulously effective base for a traditional mayonnaise. Similar sauces, such as true aïoli where garlic is used instead of the egg yolk, will not take up as much oil and have a tendency to separate.

The perfect accompaniment
A simple emulsion of egg yolk and oil can make the perfect accompaniment to a myriad of dishes—it’s all about the right oil and seasoning. It’s good to start out with a mild oil such as sunflower or cold pressed rapeseed and then finish off with something more assertive such as extra virgin olive oil, or a distinctive nut oil to taste.

The seasoning is vital too—not just for flavour, but because rather unbelievably it turns out that each ingredient plays a vital role in the chemistry of the sauce too. Salt makes the yolk particles more viscous, mustard releases a gummy glue that helps stabilise the emulsion and lemon juice or vinegar ups the water to oil ratio, allowing more fat to be added. Magic! Just make sure that all your ingredients are room temperature and go slow for a smooth ride.

Mayonnaise is known as a ‘mother sauce’ in the classic kitchen, with many traditional derivatives. Remoulade—mayo with a good dose of extra mustard and perhaps some anchovies or capers—is glorious with celeriac or any winter slaw. Tartare is a winner with fish (try glazing fillets with a two centimetre topping and browning them under the grill) and I stilI love a retro prawn cocktail with well-made marie rose sauce.

You can be creative, too. Lime zest and grated ginger are sublime with crab; tarragon and cherries make a chicken taste of summer (you’ll have to wait a while) and harissa mayo with cold turkey and couscous salad is a great way to polish off the last of the Christmas bird.

Star culinary roles
When it comes to hot emulsion sauces, the yolk gets to show off both of its star culinary roles: the yolk simultaneously thickens with the heat as if you were making a custard, and emulsifies, trapping the melted fat in tiny globules as you whisk. The yolk miraculously transforms melted butter into a luscious sauce.

Hollandaise takes patience and plenty of care. It has the potential to both scramble and curdle, but maybe it’s that sense of achievement when you serve up your eggs benedict that makes them taste even better. Once you’ve mastered the technique, you can try your hand at a more intensely-flavoured béarnaise to accompany a well hung steak, or a maltaise sauce using new season oranges, (blood orange juice is especially good)—sublime over some steamed broccoli.