Instructions:
- Marinate the Chicken: Combine chicken thigh pieces with soy sauce, mirin, sake, brown sugar, and grated ginger in a bowl. Mix well. Cover and refrigerate for at least 30 minutes.
- Dredge & Sear: Remove chicken from marinade, reserving the excess liquid. Toss the chicken pieces lightly in cornstarch until just coated. Heat oil in a large, deep skillet or Dutch oven over medium-high heat. Sear chicken in batches until nicely browned on all sides; remove browned chicken and set aside.
- Sauté Aromatics: Reduce heat to medium. Add the sliced onions, carrots, and celery to the skillet. Sauté for 3–4 minutes until the onions begin to soften slightly.
- Deglaze & Simmer: Pour the reserved marinade liquid and the 1 cup of water/broth into the skillet. Bring the mixture to a gentle boil, scraping up any browned bits from the bottom.
- Braise: Return the seared chicken to the skillet. Reduce heat to low, cover the skillet tightly, and allow it to simmer gently for 25–30 minutes, or until the chicken is very tender and cooked through.
- Reduce Sauce (Optional): Remove the lid for the last 5 minutes of cooking if you prefer a slightly thicker sauce.
- Rest & Serve: Check seasoning. Garnish generously with sliced green onions and serve piping hot over steamed rice.