Begin by patting the boneless, skinless chicken thighs dry using paper towels. Coat each thigh in cornstarch and set aside.

In a large skillet, heat 2 tablespoons of vegetable oil over medium-high heat. Add the chicken thighs in a single layer and sear for 2-3 minutes on each side until golden brown.

In the same skillet, add the minced garlic and grated fresh ginger. Sauté over medium heat for about 30-60 seconds until fragrant.

Add low-sodium soy sauce, water, and dark brown sugar to the skillet. Whisk and simmer for 2-3 minutes until slightly thickened.

Stir in rice vinegar and sesame oil. Return the seared chicken thighs to the skillet and coat evenly with the sauce, heating for an additional 2-3 minutes.

Remove from heat and stir in sliced spring onions. Serve over steamed rice.