Cut the duck breasts into thick slices. Place two slices side by side, with the meat sides touching. Insert two wooden skewers through the meat to hold the tournedos in place.
In a large pan, melt the butter. Add the duck tournedos and cook for 3 minutes on each side. Season with salt and pepper.
Add the blanched bok choy to the pan to heat it up and lightly brown it.
Remove the bok choy from the pan and set it aside.
Add the white wine and thyme to the pan. Let it evaporate for a minute.
Add the blueberry jam. Bring to a boil. Reduce the heat and let it simmer for 2 minutes.
To serve, place a bok choy and a duck tournedos on each plate. Remove the skewers. Drizzle the blueberry sauce over the duck.