Prep the veggies: Add potatoes, carrots, bell pepper, and onion to the slow cooker. Drizzle with olive oil and season lightly with salt and pepper.
Toss to coat.
Season the chicken: Pat the chicken dry and season both sides with salt and pepper. Nestle the pieces on top of the vegetables.
Mix the sauce: In a bowl, whisk soy sauce, honey, garlic, ginger, rice vinegar, sesame oil, red pepper flakes, and chicken broth until smooth.
Pour and cook: Pour the sauce evenly over the chicken and veggies. Cover and cook on Low for 5–6 hours or High for 2.5–3.5 hours, until the chicken is tender and the potatoes are soft when pierced.
Add green beans: About 30 minutes before serving, stir in the green beans.
Re-cover and finish cooking until crisp-tender.
Thicken the sauce (optional): Transfer 1/2 cup of the cooking liquid to a small bowl. Whisk in the cornstarch until smooth. Stir this slurry back into the slow cooker, cover, and cook on High for 10–15 minutes until slightly thickened.
Finish and serve: Taste and adjust seasoning with a little extra soy sauce or a squeeze of honey if needed.
Serve over rice or quinoa, and garnish with sesame seeds and green onions.