Combine chicken cubes with cornstarch, salt, and pepper in a large bowl until chicken is evenly coated in cornstarch.
Heat 2 tablespoons vegetable oil in a large nonstick skillet over medium-high heat. Working in batches, add chicken to pan in a single layer, shaking off excess cornstarch, and fry on all sides until chicken is golden-brown and crispy. Cook remaining chicken, adding additional oil to pan as needed. Transfer chicken to a plate and set aside for a moment.
In a small bowl, combine garlic, gochujang, honey, soy sauce, and rice vinegar.
Drain drippings from pan you used to fry the chicken and reduce heat to medium. Add gochujang mixture and stir frequently 2-3 minutes until sauce is thickened and reduced.
Toss chicken into gochujang sauce until evenly coated. Spear chicken with toothpicks, arrange on a serving plate, and garnish with sesame seeds and green onions. Serve immediately and enjoy!