Kartoffeln mit buntem Gemüse und Käsesauce (potatoes with colourful vegetables and cheese sauce)

Method

1. Cover the potatoes with cold salted water and bring to a simmer. Cook for 18 to 20 minutes, until a knife slides in without resistance.
2. Steam the carrot for 5 minutes, then add the broccoli and cauliflower and steam a further 5 minutes, until all are tender but not falling apart.
3. Melt the butter in a saucepan over medium heat. Whisk in the flour and cook for 1 minute, stirring constantly, without letting it colour.
4. Whisk in the warm milk a splash at a time, letting each addition incorporate fully before adding the next, until the sauce is smooth. Simmer for 3 to 4 minutes, whisking, until thickened enough to coat the back of a spoon.
5. Remove from the heat and stir in the cheese until melted. Season with nutmeg, salt and white pepper.
6. Drain the potatoes and vegetables. Arrange on plates and spoon the cheese sauce generously over the top.

Notes

• Whisk the milk in gradually, not all at once. A roux absorbs liquid best in stages; dumping in all the milk at once is what causes lumps that never fully smooth out, however long you whisk afterward.
• Cook the roux for a full minute before adding milk. This cooks out the raw flour taste, which otherwise comes through as a faint chalkiness in the finished sauce.
• Take the sauce off the heat before adding the cheese. Boiling cheese sauce can cause the cheese to split into grease and stringy solids; melting it off the heat keeps it smooth.
• Use a cheese with real flavour, not a mild pre-shredded blend, the sauce is the entire flavour of this dish, so a bland cheese makes a bland plate.

Ingredient substitutions

• Carrot, broccoli and cauliflower can be any vegetables that steam well in the same time, such as green beans or Romanesco.
• Cheddar or Gouda can be swapped for any well-flavoured melting cheese, including a blue cheese for a sharper sauce.
• A pinch of mustard powder in the sauce sharpens the cheese flavour without adding heat.