In a saucepan combine all ingredients and reduce liquid by three-fourths.
Adjust seasoning if necessary.
Place egg yolk in a separate, heat-safe bowl. In a sauce pot, bring water and salt to a simmer and gently pour over egg yolk being careful to not rupture the membrane.
Allow to poach in warm water for approximately 5-7 minutes.
Garnish rice with the poached egg yolk and scallions.
In a sauté pan, heat oil just until it dances. Sear salmon skin-side down and allow to crisp for approximately 4 minutes.
Flip over and continue to cook for 1 to 2 minutes.
Add butter and baste until skin begins to crackle and puff.
Serve over Chazuke.