Season steaks with salt and black pepper.
Fry steaks in butter and olive oil for 2-3 minutes per side until cooked to preference.
Heat vegetable oil to 190°C and fry potato matchsticks for 3-4 minutes until golden.
Drain potatoes on kitchen paper and season with salt and pepper.
Fry sliced shallots in 25g of butter for 2-3 minutes until golden.
Add mushrooms and garlic to the pan and cook for 1 minute.
Pour in white wine and simmer for 2-3 minutes.
Add chicken stock and simmer for 10-12 minutes until reduced by half.
Whisk in the remaining butter and stir in tarragon leaves.
Serve steak with fries and spoon the sauce over the meat.