Preheat your oven to 425°F (220°C) for roasting sweet potatoes and chicken.
In a large mixing bowl, whisk together toasted sesame oil, low sodium soy sauce, Gochujang, honey, grated ginger, and grated garlic until combined.
Add cubed chicken breasts to the marinade, coat well, and marinate for at least 20 minutes or up to 2 hours.
Toss cubed sweet potatoes with a drizzle of sesame oil, kosher salt, and black pepper. Spread on a sheet pan and roast for 15 minutes.
Remove sheet pan, push sweet potatoes to one side, add marinated chicken cubes to the other side, spreading evenly.
Return sheet pan to oven and roast for an additional 20-25 minutes until chicken is cooked through and sweet potatoes are tender, stirring halfway.
While roasting, prepare Yum Yum sauce by mixing Greek yogurt (or alternative), lime juice, and a pinch of salt until smooth and creamy.
Once cooked, remove pan from oven, toss kale with lime juice and add to pan to wilt slightly. Serve chicken and sweet potatoes over steamed rice, drizzle with Yum Yum sauce, and garnish with sesame seeds, cilantro, and optional toppings.