Sweetcorn soup with chicken and mushrooms

Ingredients

• 10g unsalted butter
• 1 onion,
• 1 stick celery,
• 1 x 400g can sweetcorn
• 600ml hot chicken of vegetable stock
• 10 mushrooms,
• 1 cooked chicken breast,
• Juice of 1/2 lime
• 1/2 red pepper,
• 3 spring onions,
• 1-2 tbsps crème fraiche