For the marinade, place Chinese five-spice blend, sugar, honey, Hoisin sauce, soy sauce, olive oil, sesame oil, ketchup, black pepper, and Serrano pepper in a medium saucepan and bring to simmer for about 2 minutes. Let the Serrano pepper simmer in the liquid and kind of shrivel up. This will not add heat. If you want heat, dice up the Serrano before adding to liquid. Set marinade aside to cool.
1 Tbsp Chinese Five-Spice Blend, 1 ½ Tbsp granulated sugar, 3 Tbsps honey, 3 Tbsps Hoisin sauce, 3 Tbsps soy sauce, 2 Tbsps mild olive oil, 1 Tbsp sesame oil, 1 Tbsp ketchup, 1 tsp freshly ground black pepper, 1 fresh Serrano pepper