Steak haché with pommes frites & cheat's Béarnaise sauce - Good Food Middle East

Ingredients

• 1 tbsp vegetable oil
• 4 shallots, very finely chopped
• 600g freshly ground beef (ask the butcher for something with roughly 15% fat - we used chuck)
• 8 thyme sprigs, leaves picked and chopped
• 2 tsp Dijon mustard
• 2 tbsp plain flour
• 200ml crème fraîche
• 1 egg yolk
• 6 tarragon sprigs, leaves picked and finely chopped
• dressed green salad, to serve
• 4 large baking potatoes (such as Maris Piper or Russet), peeled
• 2 tbsp vegetable oil