Preheat the oven to 200°C/gas mark 6. Roast the pigeon carcases for 10 minutes until golden. Place into a large pan and add the onion, garlic, bay leaves, water and red wine. Bring to the boil, then simmer at the lowest setting for approximately two hours, removing any ‘scum’ from the surface from time to time. Top up with additional water during this time, if necessary. Once the stock has a strong flavour, remove the bones and pour the stock into another pan, then add the lentils and cook for approximately 30 minutes, until tender. Add the chestnuts and blend in a food processor. Pass through a fine sieve into a clean pan and check seasoning. Keep warm.
Pan-fry the pigeon breasts in a hot pan, until golden all over, then add a knob of butter and cook for 1 to 2 minutes. Remove from the heat and rest for approximately one minute.
Reheat the broth and serve in deep bowls. Slice the breasts and place on top of the broth. Serve with the Sourdough bread. A little pesto or herb oil to garnish would give an extra dimension.