Score the duck skin diagonally at 5-10mm intervals
In a cold heavy pan, preferably a cast iron skillet, lay the duck breast skin down.
Put the skillet over a medium-low heat. After a few minutes you will start to see fat rendering from the duck.
Continue cooking until the skin is a light gold colour. We are going to brown it again, so don’t go too far. Should have accumulated 3-5 Tbsp duck fat. Keep that for roasting something else.
Allow the duck breasts to cool a little.
Add a sprinkle of salt to each breast and put into individual sous vide bags.
Remove the air and seal with a vacuum sealer, or the immersion method.
Sous vide for 1 hour 30 minutes at 58 degC.
Plunge the bags into cold water until cool enough to handle.
Bring the skillet to a medium heat.
Lay the duck breasts in the skillet again skin side down and sear until golden brown.
Allow to rest for 10 minutes.
Lay skin side down on a cutting board. Slice into thirds length ways. Then slice into thin slices width ways.
Spring rolls
Separate the egg white from the yolk, retaining both.
Whisk the egg yolk to break it up a bit.
Toss together the diced duck breast, basil, parsley, green onions, ginger, whisked egg yolk, yuzu kosho (or salt), and pepper.
Lay a spring roll wrapper on a board oriented as a diamond.
Spoon about 2 Tbsp of the mixture on to the wrapper, half way between the front corner and the horizontal centre line.
Roll the wrapper up. When you get to half way, brush some egg white on to the three remaining corners. Fold the two side corners in, then keep rolling.
Dipping sauce
Bring the first 6 ingredients to a simmer and simmer for 10 minutes.
Blend the ingredients together with an immersion blender.
Simmer a further 5 minutes.
Add the diced chili (or make optional) and sprinkle on the fried shallots before serving.