How to cook beef wellington | DAILYFIX

Ingredients

• 800g beef fillet, at room temperature
• 2 tbsp oil
• 2 tsp prepared English mustard
• 2 tbsp butter
• 1 onion, chopped
• 2 cloves garlic, chopped
• 250g Portabellini mushrooms, halved
• 2 tbsp chopped parsley
• salt and pepper
• 1 x 400g ready-rolled puff pastry, defrosted
• 1 egg, separated
• 2 tbsp milk (mix with yolk for egg wash)