Combine wet ingredients: In a small bowl, whisk together 3 to 4 tablespoons soy sauce, 1 to 2 tablespoons gochujang paste, 1 tablespoon granulated sugar, 1 tablespoon rice vinegar, and 1 to 2 teaspoons toasted sesame oil until smooth and well combined.
Mix the spices: In another small bowl, combine 1 teaspoon ground ginger, 1/2 teaspoon garlic powder, and 1 teaspoon cornstarch. This blend will infuse the chicken with warming spice and help thicken the glaze.
Season your chicken: Pat dry 1 to 1.25 pounds diced chicken thighs with paper towels, then season generously with salt and freshly ground black pepper on all sides.
Heat the oil: In a large skillet over medium-high heat, warm 1 tablespoon olive oil for about 1 minute until shimmering.
Sear the chicken: Add the seasoned chicken pieces and cook without stirring for 3 to 4 minutes until the bottoms are golden brown, then stir and cook for another 3 to 4 minutes until mostly cooked through.
Add the glaze: Pour the prepared sauce over the chicken and stir gently to coat all pieces evenly. Cook for 2 to 3 minutes, stirring occasionally, until the sauce thickens and coats the chicken in a glossy layer.
Finish cooking: Continue cooking for 1 to 2 minutes more until the chicken is fully cooked through and the glaze reaches your desired consistency.