Chop the chicken thighs into 1-inch pieces. Add them to a medium bowl with 1/3 cup cornstarch and toss until the chicken is completely coated. Set aside.
Make the sauce by mixing the sesame oil, 1 tablespoon of cornstarch, soy sauce, hoisin sauce, brown sugar, chicken broth, water, chili sauce, and 2 tablespoons of minced garlic in a medium bowl.
Place the vegetable oil into a deep pan over medium-high heat and allow the oil to get hot. (Test the heat by throwing in a pinch of cornstarch, when it sizzles immediately it is hot enough for the chicken.) Place the chicken into the hot oil and cook until crispy, about 8 minutes. Flip the chicken periodically so it cooks evenly. Then transfer the chicken to a paper towel-lined plate to drain.
To a large skillet, add 1 tablespoon of oil over medium-high heat. Add the ginger, garlic, and chopped green onions and cook until fragrant.
Add the sauce to the pan and bring to a slow boil. Add in the chicken, stir to coat, and then reduce the temperature to medium-low. Stir often to thicken the sauce.
Once the sauce has thickened to your liking, top the chicken with sesame seeds and sliced green onions before serving over cooked rice.