Make the Marinade: Heat sesame oil in a saucepan over medium heat. Add ginger and garlic; sauté until fragrant, about 1 minute. Incorporate soy sauce, rice vinegar, brown sugar, ketchup, and smoked paprika. Mix cornstarch with cool water, add it to the sauce, and bring to a boil. Simmer until thickened, about 3-4 minutes, then remove from heat.

Marinate the Chicken: Reserve ½ cup of the marinade for basting later. Cool the remaining marinade for 5 minutes. Toss the chicken thighs in the marinade, ensuring they are well-coated, and let them marinate in the fridge for 30 minutes to 4 hours.

Grill the Chicken: Preheat your grill to medium-high heat and grease the grates with vegetable oil to prevent sticking. Place the marinated chicken on the grill, cooking for 4-6 minutes per side. Baste with the reserved marinade while grilling, flipping occasionally. Ensure the chicken reaches an internal temperature of 165°F for safe eating.

Serve: Once cooked through, transfer the grilled chicken to a platter. Serve it alongside steamed rice and colorful grilled vegetables for a delightful presentation.