Add the potatoes and cook for two minutes without colouring the potatoes.
Add the leeks, shallots and garlic and cook for a further 4 minutes without colouring.
Add 1500ml of vegetable stock and horseradish; bring to the boil and simmer for 6 minutes then remove from the heat.
Heat a clean pan and add the remainder of the oil and stock with the spinach and watercress and cook until the bitterness of the watercress is reduced.
Add the spinach and watercress to the stock, potatoes, leeks, garlic and shallots and liquidise until smooth and bright green in colour. Pass through a strainer to ensure the soup is completely smooth.
Bring a pan of water to the boil with a little oil and white wine vinegar, poached quails eggs for one minute.
Season the soup and pour into serving bowls.
Add three poached quails eggs to each bowl and finish with a little drizzle of olive oil.