Halve the orange and slice thickly. Discard any seeds and place the slices in a small saucepan. Cover with water, bring to a boil and simmer for 5 minutes to remove the bitterness. Drain the orange slices and set aside.
Pierce the skin of the duck breasts diagonally with a small knife (this will help release the fat). Rub the skin with salt.
Place a steel or cast-iron frying pan over steady heat and cook the breasts for 20 minutes, turning once, until they are medium-rare. Transfer to a warm plate, cover and keep warm.
Heat the sediment in the frying pan until it begins to darken and caramelize. Add the wine and stir to loosen the sediment. Add the ground coriander, cumin or fennel seeds, sugar and orange slices.
Boil quickly and reduce to coating consistency. Sharpen with the lime or lemon juice and season to taste with salt and cayenne pepper. Transfer the orange sauce to a bowl, cover and keep warm.
Remove the crusts from the bread and cut the bread into short fingers. Heat the garlic oil in a heavy frying pan and brown croutons. Season with salt, then transfer to paper towels.
Moisten the salad leaves with a little sunflower or peanut oil and distribute among four large serving plates.
Slice the duck breasts diagonally with a carving knife. Divide the meat into fourths and lift onto each salad plate. Spoon on the orange sauce, sprinkle with croutons decorate with a sprig of fresh cilantro and serve warm.