Editorial: Kockums JernverkPublished: 2026-11-06

Biff Rydberg – Swedish beef fillet with fried potatoes, onion and egg yolk

Name: Biff Rydberg – Swedish beef fillet with fried potatoes, onion and egg yolk
Prep time: 15 min
Cook time: 35 min
Total time: 50 min
Cuisine: Swedish
Ingredients: 500 g waxy potatoes; 2 brown onions, finely chopped; 300 g beef fillet or sirloin; 2 tbsp neutral oil, plus 2 tbsp for the beef; 40 g butter; Salt and freshly ground black pepper; 2 egg yolks, ideally in half shells; 2 tbsp chopped parsley; 100 ml double cream; 1 tbsp Dijon mustard; A pinch of salt

Serves 2 · 50 minutes · Ergonomic frying pan

Biff Rydberg is three simple things fried separately: potatoes, onion and beef fillet. A carbon steel pan takes the high heat that crusts the beef in a minute, before it has time to stew.

Biff Rydberg is a Swedish classic of diced fried potatoes, soft fried onion and cubes of beef fillet, served in rows with a raw egg yolk and mustard cream. The secret is to fry each part on its own: the potatoes slowly until golden, the beef fast over very high heat so it stays pink inside.

Biff Rydberg in three rows of fried potatoes, onion and beef with an egg yolk in its shell, in an ergonomic carbon steel frying pan

Ingredients

Serves 2

500 g waxy potatoes
2 brown onions, finely chopped
300 g beef fillet or sirloin
2 tbsp neutral oil, plus 2 tbsp for the beef
40 g butter
Salt and freshly ground black pepper
2 egg yolks, ideally in half shells
2 tbsp chopped parsley

Mustard cream

100 ml double cream
1 tbsp Dijon mustard
A pinch of salt

Method

Heat the oven to 100 °C. Peel the potatoes and cut them into 1 cm dice. Rinse in cold water and dry thoroughly in a tea towel.
Heat 2 tbsp oil and half the butter in the pan over a medium heat. Fry the potatoes for 15–20 minutes, stirring now and then, until golden and cooked through. Season with salt and keep warm on a plate in the oven.
Finely chop the onions. Fry them in the remaining butter over a medium-low heat for 8–10 minutes until soft and golden. Season lightly and put them in the oven next to the potatoes.
Lightly whip the cream, stir in the mustard and season with salt.
Cut the beef into 1.5 cm cubes. Wipe out the pan and heat it over a high heat with 2 tbsp oil until the oil shimmers. Fry the beef for 1–2 minutes so it is browned all over but still pink inside. Season with salt and pepper.
Arrange the potatoes, onion and beef in three rows in the pan, set the egg yolks in the middle and scatter over the parsley. Serve straight away with the mustard cream.

Why it works

Carbon steel handles very high heat, so the beef forms a dark crust before it can release its juices and turn grey. The straight, slightly higher sides of the pan keep the potatoes in place as you turn them.