1. Heat a large, deep frypan on medium-high. When hot, add 1 tablespoon olive oil and the asparagus. Season with a little salt and cook for 2-3 minutes, shaking the pan every now and then, until the asparagus is charred but still tender-crisp. Remove from the pan and set aside. Wipe the frypan out to use again.

2. Place the butter and miso into a small bowl and, using a fork, mash them together. Place the same frypan on medium heat, add the butter-miso mixture and stir to melt. When mostly melted, add the Sichuan pepper flakes, black pepper and vegetable stock. Stir and cook for 1 minute until the mixture is well combined.

3. Bring a large pot of salted water to the boil and add the udon noodles. Cook according to packet instructions, about 1 minute. When ready, using tongs, remove the noodles from the water and place them straight into the miso sauce, dragging over some of the water the noodles cooked in. Retain some of the cooking water in case you need to thin the sauce.

4. Toss the noodles in the sauce; if it's too thick, add a little more noodle cooking water. Taste and season with salt and more black pepper, if needed. Add the asparagus to the noodles and top with spring onion and sesame seeds. Serve warm.

Tip: The sauce is both incredibly decadent and achingly simple to make – vegan butter and miso paste create a creamy flavour base, though if you aren't vegan, regular unsalted butter will work just fine. 

*If you don't have Sichuan pepper flakes, you can use white pepper or just add more black pepper.

Neil Perry's traditional cacio e pepe recipe