Place cubed potatoes in a pot of cold salted water, bring to a boil, and simmer for 15-18 minutes until fork-tender.
In a small mixing bowl, whisk together honey, soy sauce, minced garlic, and grated ginger to create the glaze.
Heat vegetable oil in a large skillet over medium-high heat. Add chicken pieces in a single layer and sear until golden brown and cooked through (internal temperature 165°F/74°C).
Reduce skillet heat to medium, pour the honey-soy glaze over the chicken, and simmer for 3-5 minutes until the sauce reduces to a thick, sticky consistency that coats the chicken.
Drain the potatoes thoroughly and return to the warm pot. Mash using a potato masher or ricer.
Incorporate butter, warmed milk, salt, and pepper into the potatoes, whisking until smooth and creamy.
Portion mashed potatoes onto plates, top with sticky chicken, and garnish with sesame seeds and sliced green onions.