Peel and finely slice the onions and garlic cloves. Pick the sage from the stalks and cut into fine slices.
In a large saucepan, heat the sunflower oil until hot. Add the onions and garlic and cook for 6-7 minutes until nicely caramelised. Stir in the butter and cook the mixture for a further 3 minutes on a medium heat. Add the cider to the pan and reduce by half. Once reduced, add the thyme sprigs and cover the mixture with water. Bring to the boil and then simmer for 15 minutes until the onions are tender.
After 15 minutes, remove the pan from the heat and rest for 5 minutes. Place the mixture into a blender and blitz for 5 minutes until smooth. Return the soup to the saucepan and add the seasoning.
Serve the soup in a bowl and finish with the fresh sage.
«Use a very dry cider to balance the sweetness of the caramelised onions. »