Line a pan with parchment and grill the salmon skin-side down over medium for 3-4 minutes. Flip and grill 3-4 minutes more until browned (for fresh salmon, salt it, leave 10 minutes, wipe dry, then grill).
While hot, peel off the skin, remove the bones and flake the flesh into large pieces. Crisp the skin further in the pan and chop finely.
Make the dashi by diluting the shiro-dashi with boiling water (hot green tea is fine too).
Put rice in a bowl, top with the flaked salmon and chopped skin, and add mitsuba, bubu-arare, shredded nori, white sesame and wasabi.
Pour the piping-hot dashi over and serve pickles on a small dish. Nibbling pickles between mouthfuls refreshes the palate with their salt and crunch.
Flake and refrigerate the leftover second fillet to use right away in the next morning's rice balls or another chazuke.