Chicken Stroganoff

Ingredients

• 1 tbsp olive oil
• 1 tbsp butter
• 400g/14oz chestnut mushrooms, halved
• 2 red onions, chopped
• 2 garlic cloves, finely chopped
• 3 skinless, boneless chicken breasts, cut into bite-sized pieces
• 300ml/10fl oz chicken stock
• 1 tbsp tomato purée
• 1 tbsp wholegrain mustard
• 1 tbsp sweet smoked paprika
• 250ml/9fl oz soured cream (use reduced fat soured cream if preferred)
• small handful chopped tarragon or parsley
• salt and freshly ground black pepper