Dredge the duck pieces in flour. In a large sauté pan, fry the duck in a mixture of oil and butter until golden and crisp. Add the onions, the garlic and the smoked bacon pieces and sauté until lightly coloured.
Next add the Champagne, thyme and bayleaf, bring to the boil and cook, uncovered for half an hour. Then add the turnips and the leeks and cook for twenty minutes or so, until the duck is almost done. Finally add the peas and the lettuce and cook for a further twenty minutes. The sauce will be pale, and slightly thickened. Season to taste with salt and pepper.