Chicken Chashu

Bahan-bahan (4 porsi)

• 2 boneless, skin-on chicken thighs ((about 7.4 oz (210 g) each; use the largest chicken thighs you can find))
• 2 g reen onions/scallions ((you can substitute leek or Tokyo negi))
• 5 slices ginger ((peeled and thinly cut, from 1 knob))
• 2 tsp neutral oil ((for searing))
• 1 cup water
• ½ cup mirin
• ½ cup soy sauce
• ½ cup sake
• 2 Tbsp sugar