Prep the sauce. Whisk gochujang, soy sauce, honey, rice vinegar, garlic, ginger, sesame oil, and water in a small bowl until smooth. Set aside.
Slice and season the chicken. Cut chicken thighs into thin, bite-sized strips. Pat dry with paper towels so they brown instead of steam.
Sear the chicken. Heat oil in a large skillet over medium-high heat. Add chicken in a single layer. Cook 3–4 minutes without stirring until golden edges form. Flip and cook another 2–3 minutes until nearly cooked through.
Add the sauce. Pour the sauce over the chicken. Stir and cook 2–3 minutes until the sauce thickens, turns glossy, and coats every piece. Look for bubbles and a sticky sheen.
Assemble the bowls. Divide rice among four bowls. Top with sauced chicken, cucumber, carrots, green onions, and sesame seeds. Serve immediately while the chicken is hot and the veggies stay crisp.