1. Preheat the oven to 425°. In a large bowl, mix the vegetable oil with the five-spice powder. Add the chicken, season with salt and pepper and toss. Arrange the chicken on a foil-lined baking sheet. Roast for about 35 minutes, turning twice, until cooked.
2. Meanwhile, in a blender, combine the hoisin sauce, chili sauce, rice vinegar, stock, ginger, garlic and sesame oil and puree until very smooth. Transfer to a saucepan and simmer until slightly thickened, 5 minutes.
3. Transfer the chicken to a bowl and toss with the sauce, until completely coated.
4. Preheat the broiler and position a rack 8 inches from the heat. Return the chicken to the baking sheet and broil for about 10 minutes, brushing with the sauce and turning occasionally, until glazed and sticky.
5. Add the sesame seeds to a bowl. Dip the chicken in the seeds to coat; serve.