Chateaubriand with Béarnaise Sauce - Irish Beef

Ingredients

• 675 g (1¬? lb) thick end of a whole fillet (called the chateaubriand)
• 1 tbsp olive oil
• ½ tsp sea salt
• ¬º tsp freshly ground black pepper
• 250g (9oz) unsalted butter
• 2 tbsp dry white wine
• 2 tbsp tarragon vinegar
• 2 tbsp chopped fresh tarragon
• 1 shallot, finely chopped
• ½ tsp ground white pepper
• 2 egg yolks
• ¼ lemon, pips removed
• 1 tbsp chopped fresh flat-leaf parsley
• pinch cayenne pepper
• sea salt and freshly-ground black pepper
• fresh watercress sprigs, to garnish
• chips, to serve
• Ingredients
• Method