Whisk together first 7 ingredients: Garlic, ginger, chicken broth, soy sauce, gochujang, mirin and sesame oil. Set aside.

Heat oil over medium-high heat in a cast iron or other heavy skillet until shimmering. Season chicken thighs with salt and black pepper.

Place chicken thighs in skillet, skin side down and cook 4-5 minutes or until skin is nicely browned. Transfer to a plate.

Refresh oil if needed. Add the onion, reduce heat to medium-low and cook 5-6 minutes or until onion is beginning to soften.

Return chicken thighs to skillet along with sauce combination. Bring to a boil.

Reduce heat to medium-low and simmer 25-30 minutes or until chicken thighs are thoroughly cooked through and tender.

Using a ladle, transfer some of the liquid to a small bowl and whisk in the cornstarch. Pour into the skillet and continue simmering 2-3 minutes or until thickened.

Serve, garnished with sesame seeds and thinly sliced scallion and cooked brown rice.