Begin by preparing a large bowl. Add the gochujang sauce, soy sauce, sesame oil, rice vinegar, brown sugar, ground ginger, and garlic. Stir these ingredients together until they are well combined, creating a beautiful, rich marinade.
Next, take your diced chicken and add it to the bowl. Make sure each piece is well coated in the marinade. Cover the bowl and place it in the fridge to marinate. Ideally, let it marinate for at least 1 hour, but for a deeper flavor, you can leave it for up to 8 hours.
Once the chicken has marinated, it’s time to cook! Heat a large skillet over medium-high heat and add the olive oil. Once the oil is shimmering, use a slotted spoon to transfer the marinated chicken into the skillet, discarding the leftover marinade.
Cook the chicken for about 5 to 7 minutes, flipping intermittently to ensure even cooking. You want it to be golden brown and cooked through. As it cooks, enjoy the enticing aromas that fill your kitchen!
While the chicken is cooking, grab a small bowl. Add the cornstarch and cold water, stirring until the cornstarch is completely dissolved. This will be your thickening agent for the sauce.
After the chicken is fully cooked, add the cornstarch slurry to the side of the pan. Don’t dump it over the chicken—this ensures an even coating of sauce. Turn the heat to medium-low and gently stir the slurry into the sauce.
Keep stirring for about 1 to 2 minutes, watching as the sauce thickens to your desired level. You’ll notice a nice glossy finish as it coats the chicken beautifully.
Remove the pan from the heat and add in the diced green onions and a sprinkle of sesame seeds. Give it a gentle stir to combine everything.
Serve the Spicy Korean Chicken immediately. It’s best enjoyed warm and fresh, but if you have leftovers, they can be stored in the fridge for up to 5 days.