In a large bowl, whisk together honey, soy sauce, apple cider vinegar, minced garlic, grated ginger, and black pepper until well combined.
Add the chicken thighs to the marinade, ensuring they are fully coated. Cover and refrigerate for at least 30 minutes, or up to 2 hours for more flavor.
Preheat your grill or a large skillet over medium-high heat and add the vegetable oil.
Remove the chicken from the marinade, reserving the marinade for later.
Grill or pan-sear the chicken for about 6-7 minutes on each side, or until the internal temperature reaches 165°F.
While the chicken is cooking, pour the reserved marinade into a small saucepan and bring to a boil. Reduce heat and simmer for about 5 minutes to thicken slightly.
In the last few minutes of cooking, add the pineapple chunks to the grill or skillet, cooking until they are caramelized and heated through.
Once the chicken is cooked, remove it from the heat and let it rest for a few minutes. Slice the chicken and serve with the grilled pineapple on top. Drizzle with the thickened marinade and garnish with chopped green onions and sesame seeds if desired.