Sirloin steak with a Provencal herb crust and baked potato side dish

Ingredients:

• 0.7 kg of marbled sirloin steak, 1 cm thick (from the loin)
• 4 small thick-skinned Russet Burbank potatoes, scrubbed
• 2 tbsp hot mustard, plus extra for serving
• 2 tsp chopped Provencal herbs
• 5 tbsp (75 g) butter
• 2 tbsp chopped chives or green onions

Preparation:

1. Prick the potatoes in several places with a fork and microwave until tender, about 15 minutes.
2. Meanwhile, prick both sides of the steak with a fork. In a bowl, combine the mustard and herbes de Provence and rub the mixture all over the steak.
3. Heat a large cast-iron skillet over medium-high heat. Add 1 tablespoon (15 g) of butter. Once melted, add the steak and sear on one side until golden brown, about 7 minutes. Flip and sear on the other side for about 4 minutes for medium-rare. Transfer the steak to a cutting board, season with salt and pepper, and top with 1 tablespoon (15 g) of butter. Let rest for at least 5 minutes.
4. Return the pan to medium-high heat. Add the potatoes and swirl them around the pan to coat them with the steak juices. Cook until crispy, about 3 minutes.
5. Combine the remaining 3 tablespoons (45 g) butter with the green onions and season with salt. Thinly slice the steak diagonally. Serve with potatoes, onion butter, and mustard.