- With both racks in the middle positions, preheat the oven to 425°F (220°C).
- In a square glass baking dish, stand the leek pieces cut side up and add the garlic and butter. Season with salt and pepper. Cover with foil and cook for 40 minutes. Remove the foil and cook for another 5 minutes. Remove the outer layer of the leeks and set aside for the red wine sauce or for another use.
- Meanwhile, cut the onions into ½-inch (1.5 cm) rounds. Set aside any onion scraps along with the leek scraps for the red wine sauce or for another use.
- Place the onions on one half of a non-stick baking sheet and drizzle with the lemon juice. On the other half of the baking sheet, place 8 slices of potato at a time, letting them overlap to form small fans. Drizzle the oil over the vegetables. Season with salt and pepper. Cook at the same time as the leeks for 25 minutes or until the onions are tender and the potatoes are golden. Keep warm.
- In a skillet over medium heat, brown the duck breasts fat side down for 10 minutes or until golden and crispy. Flip over and cook on the flesh side for 2 minutes for rare or until the desired doneness. Season with salt and pepper. Let rest on a plate for 10 minutes.
- Slice the duck. Serve with the roasted vegetables and the red wine sauce. Sprinkle with a small amount of curry powder, to taste.
Duck breast comes from farmed ducks while magret refers to the breast of a larger duck that has been force-fed to produce foie gras (a fatty liver).
You can replace the duck breasts with 4 medallions of beef top sirloin, each 1 ½ inches (4 cm) thick, cooked in 3 tbsp of butter in a very hot skillet for 3 minutes on each side.