Soak the gelatine sheets in cold water for the red cabbage espuma.
Transfer all remaining ingredients to the blender and blend to make a completely smooth mass in 10 minutes.
Transfer the mixture to a pan and briefly bring to the boil.
Remove from the heat, add the soaked gelatine and season further with salt and flavorings of your choice.
Pour over into a 1-liter siphon and aerate with 2 gas cartridges.
Keep the mass warm while serving at 65°C.
Pick the meat from the confit duck legs and season with melted duck fat.