An extraordinary and addictive combination of flavours. I am sure that a diluted beef stock cube or ready-made stock will work well if you haven’t coincidentally roasted and boiled a large beef bone recently(!)
[If you have time to make some beef broth, butchers will give you beef bones for free if you ask and you can freeze them. Roasting the bones before making broth will render out the fat (melt it from the bone), which you can pour off and then use to make delicious beef dripping roast potatoes or chips. It will keep for ages covered in the fridge and turns the most perfect waxen white when it’s cool. The resulting broth (made from covering the roasted bones water and simmering with an onion, a leek, a carrot and a bit of celery) can work for Chinese and Vietnamese noodle soups (add things like star anise, cinnamon, spring onions and rice wine to enrich flavour), as well as pearl barley style affairs. The broth can enrich future beef roast dinner gravies and you can always cook a few fresh vegetables in the broth and have with some chives and a poached egg and toast as a light meal. Also you can freeze it.]
I first had this sauce when I was working as a waitress at the Italian restaurant Artusi in Peckham last year, where the chefs were a dab hand at buttery emulsions. I’ve never made it before, but as we had some beef broth going spare and lots of butter left over from last week’s prolific pastry making, I thought I’d give it a go, adding in a few tablespoons of cooked-down diced mushrooms that were in the fridge. These are not essential, but they did enrich the flavour further.
Shaking the pan and seeing the broth and butter emulsify is very satisfying and makes you (me) feel like a professional.
A few ladlefuls of beef broth, around 300ml
75g unsalted butter (and a little more)
2 sprigs of rosemary, leaves(?) removed and finely chopped
the freshly grated zest of 2 small unwaxed lemons
the juice from 1/2 a lemon
*optional* two heaped tablespoons of cooked down diced mushrooms or a few dried porcini mushrooms re-vamped with boiling water and chopped up
tagliatelle or other long-stranded pasta (around 120g p/p, hunger dependent)
How to make
Put a large pan of water on to boil (at least 2 litres), with 1 tablespoon of salt.
Melt the butter on a low heat in a large frying pan until it’s frothy. Add the rosemary. (wow the smell!) Add in the mushrooms and grate in the lemon zest and stir a little. Add in a ladle of beef broth and shake the pan until they turn cloudy and emulsified, add a few more ladles and keep simmering and shaking. Season well with salt. Taste it to check. Simmer and reduce it a little. Turn off the heat.
Meanwhile cook the pasta.
When it’s al dente, drain. Shake the sauce pan again and add a small bit more butter and the lemon juice and shake. Add the pasta and keep tossing the pan until it’s coated with the emulsion. Garnish by grating a little more lemon zest over the top. Eat immediately.