Julienne the cucumber, thinly slice the onion and soak in water, then drain. Chop the mizuna and thinly slice the pork loin. Mix all dressing ingredients in a container to prepare the dressing.

Boil water in a pot, cook the vermicelli noodles according to package instructions, then drain. In the same pot, add a pinch of salt and cook the pork slices one by one until done. Drain and cool in water. Cut the vermicelli into manageable lengths.