Gather all ingredients: cut chicken thighs, dice onion, slice carrots, and clean mushrooms. Mince garlic, and have the other ingredients ready.

Add chicken thighs, onion, carrot, mushrooms, and garlic to the slow cooker. Pour in gochujang, soy sauce, brown sugar, sesame oil, and chicken stock. Mix thoroughly until the chicken is coated.

Cover and cook on high for 2-3 hours or on low for 4-5 hours. The longer cooking time on low enhances flavors and tenderness.

In the last hour on high or last two hours on low, make a cornstarch slurry and add it to the stew to thicken the sauce.

Taste the stew and add salt and black pepper as needed to elevate flavors. Stir to incorporate seasoning.

Ladle stew into bowls, garnish with chopped spring onions, and serve hot with rice or noodles.