Okay, the ‘Time needed’ entry is slightly misleading: although cooking the asparagus really does take less than 15 minutes, the curing and dehydrating of an egg yolk is a longer undertaking (very little work, but about 30 hours of waiting). But please try it! Cured and dehydrated egg yolk can be grated on a variety of boiled greens, or used as a seasoning for pasta dishes. It has a similar salty, umami quality to Parmesan or bottarga, although there’s also the creamy butteriness of egg yolk that clings to and coats hot vegetables. You’ll only need one yolk for this dish, but given the effort it’s worth curing 3 at once and using them as a Parmesan substitute for the next week or so.
Asparagus is best when cooked simply: a quick dance in boiling water until the spears just begin to flop. For this particular recipe, the thinner the spears the better, as there’s more surface area for the grated egg to cling to. There’s a variety of things I’d serve this with, from cold cuts of roast beef and ham, recently carved from the bone, to crab tarts or poached trout. If English asparagus is out of season, or you’d like more bulk, the asparagus could be substituted or supported by frozen peas; blanched, like the spears, for barely 4 minutes.
- Yield: 6 Servings
- 750 g asparagus
- 5 tablespoons extra-virgin olive oil
- ½ lemon juice and finely grated zest
- Sea salt and freshly ground black pepper
- Fine table salt, for curing
- Caster sugar, for curing
- Leaves from 10–20 sprigs thyme
- 3 egg yolks (ideally Burford Browns)
- To cure the egg yolks, find a small plastic or other non-reactive container that will comfortably hold the yolks with a few centimetres of space around each one. Fill it 1–2 cm deep with fine table salt, then add the same amount of caster sugar (you could measure the weight of the salt and replicate with sugar, but by eye is fine). Add the thyme leaves and mix thoroughly. Tip half of the curing mixture into a separate bowl. Break the eggs, reserving the whites for another use (such as Celeriac baked in a salt and thyme crust), and gently place the egg yolks on the curing mixture in the container, then sprinkle the remaining mixture over the top. Cover with a lid or clingfilm and leave in the fridge for 24 hours.
- After 12 hours, check the yolks. The tops might be bare. If so, spoon any excess curing mixture from the sides of the container to cover the yolks and leave for another 12 hours.
- Once 24 hours is up, the yolks will be firm to the touch and will look like boiled sweets. Preheat the oven to its very lowest setting no more than 50°C. Take the yolks out of the curing mixture and gently remove any excess with a clean damp cloth. Put the yolks on a silicone baking mat or non-stick baking sheet and leave in the oven for 6–8 hours, or until they have shrivelled to look like the surface of the moon. They’ll keep in an airtight container at room temperature for at least a week.
- To cook the asparagus, bring a large pan two thirds full of heavily salted water to the boil. Bend each spear from tip to base. They will snap at the point where the fleshy stem becomes woody. Discard the woody ends. When the water is at a rapid boil, add the asparagus and cook for 3–4 minutes. Drain the asparagus as soon as the thicker ends are tender, and well before they start to dull in colour and flavour.
- Meanwhile, mix together the oil, lemon zest and juice. Put the asparagus on a serving dish or return them to their pan. Coat them with the dressing and season with 10 turns of the pepper mill (remember that the cured yolk will add salt). Finely grate over 1 cured egg yolk using a microplane grater or something similar, and serve immediately.