For the soup, heat the oil in a pan and gently fry the onion and garlic for 2-3 minutes. Add half of the spinach and the vegetable stock and simmer for 4-5 minutes. Add the cream and heat through, then stir through the remaining spinach. Using a hand-held blender, blend the soup until smooth.
For the poached egg, pour the white wine vinegar into a non-reactive pan with 150ml/5fl oz boiling water, bring to a gentle boil and stir to create a 'whirlpool'. Crack the egg into the middle of the 'whirlpool' and cook for 2-3 minutes, or until the white has just set. Remove with a slotted spoon and drain on kitchen paper.
To serve, pour the soup into a warm serving bowl and place the poached egg into the centre. Season with freshly ground black pepper.
