Flank Steak with Shallot pan sauce

Flank Steak with Shallot pan sauce: 

Ingredients
2 tbsp beef tallow
1kg flank steak (bavette)
Sea salt, to season
3 tbsp olive oil
4 large potatoes, washed
4 shallots, thinly sliced
4 cloves garlic, chopped
100ml red wine
1 cup (250ml) beef stock
25g butter
2 tbsp chopped flat leaf parsley
Method
1. Preheat oven to 180°C fan forced (356°F).
2. Cut potatoes with a crinkle cutter into 5mm thick slices. 
3. Toss in 1 tbsp of oil and season with salt. 
4. Place on a large oven tray lined with baking paper in a single layer. 
5. Bake for 25-30 mins, until golden and crisp. 
6. Melt tallow in a large frying pan on high heat. 
7. Season steak with salt, then sear in pan for 2-3 mins each side until well charred, and cooked medium rare.  
8. Set steak aside to rest
9. Add remaining oil and shallots to the frying pan, cook, stirring for 2-3 mins, until softened and starting to brown
10. Add garlic, stirring for 1 min. 
11. Reduce heat to medium and stir in wine, cook until almost evaporated. 
12. Pour in stock, bring to a simmer, stirring. 
13. Add butter and cook, stirring until sauce is emulsified. 
14. Carve steak, serve topped with shallot sauce and crinkle cut chips, garnish with parsley.