Marks & Spencers still have some English asparagus left on their shelves so I decided to try to make the most of it before it’s finally gone. Generally at this time of year when the season is technically over the quality is not great and the best option is to make soup; in any case, if I made it earlier in the summer I’d feel like I’m wasting good asparagus because the vibrant new season’s showings are unquestionably at their best when as unadulterated as possible.
I was playing around with using oats as a thickener in this soup last year and I wasn’t very happy with the results: the main reason, I think, was that I wasn’t using any dairy so I decided to replace some of the stock with milk and it made a big difference. Unfortunately, it’s kind of hard to work out how much grain you need to get a good consistency and I really just relied on a mixture of intuition and blind luck. Next time I might cook the oats separately and add in stages whilst blending.
As for the garnishes, the burnt onion powder probably strikes as quite unusual: I robbed got the inspiration for that from a recipe Daniel Clifford did on Great British Menu recently. I followed the instructions on the BBC website but found they didn’t quite work: he has you bake the onions pretty much whole at a low temperature for four or five hours but they still had way too much moisture to grind. In fact, I ended up with a paste I had to put back in the oven to dehydrate at 30°C overnight.
Given its affinity with asparagus the egg is a much more obvious companion; I used Douglas Baldwin’s trusty sous vide guide to figure out what temperature to cook the yolk to thicken it ever so slightly and because the whites don’t coagulate much at that temperature I could just peel the albumin away after cracking the shell. A poached egg would work well here too, I reckon.
For the burnt onion powder
1 onion, halved
For the egg yolks
4 large eggs
For the soup
3 shallots, finely chopped
60g rolled oats
400ml veal stock
300g asparagus, woody stalks removed and sliced into 1cm pieces
5ml fish sauce
2.5g white pepper
2.5ml lemon juice
- For the burnt onion, place a frying pan over a high heat and place the onion cut side down.
- When the cut side has blackened, turn the onion on one of its unburnt sides to blacken.
- Repeat until the onion is black all over.
- Preheat the oven to 30°C.
- Blitz the black onion in a food processor until finely chopped.
- Spread the onion pieces over a baking tray and place in the oven.
- Dehydrate the pieces in the oven for 12 hours.
- When fully dried, place in a spice grinder and grind to a fine powder.
- To prevent clumping, store in an airtight container until needed.
- For the eggs, place in a temperature controlled water bath set to 62°C for 40 minutes.
- Crack the eggs and separate the egg yolk from the white.
- Reserve the yolks in a bowl of water until needed.
- For the soup, over a low heat melt 10g of butter in a pot and add the shallots.
- Sauté the shallots until softened, around 5 minutes.
- Pour in the milk and bring to a simmer.
- Add the oats and cook for around 10 minutes, stirring occasionally to stop them from catching on the bottom.
- Add the veal stock, asparagus, fish sauce and white pepper and cook until the asparagus is soft, approximately 5 minutes.
- Transfer the soup to a blender and blend until very smooth.
- Stir in the remaining butter and blend to incorporate.
- Add the lemon juice and correct the seasoning if required.
- To serve, place one of the egg yolks in each bowl, pour the soup over it and then sprinkle over some of the onion powder