Place soy sauce, honey, rice wine, hoisin sauce, ketchup, brown sugar, garlic, five-spice powder, black pepper, cayenne pepper, and curing salt in a saucepan. Bring to a boil on high heat; reduce heat to medium-high. Cook for 1 minute. Remove from heat. Cool to room temperature.
Cut pork roast in half lengthwise. Cut each half again lengthwise forming 4 long, thick pieces of pork.
Transfer cooled sauce to a large mixing bowl. Stir in red food coloring. Place pork sections into sauce and coat each piece. Cover with plastic wrap and refrigerate 4 to 12 hours.
Preheat grill for medium heat, 275 to 300 degrees F (135 to 150 degrees C) and lightly oil the grate. Line a baking sheet with parchment paper.
Remove sections of pork from marinade and let excess drip off. Place on prepared baking sheet. Sprinkle with kosher salt to taste.
Transfer pork sections to grate over indirect heat on the prepared grill. Cover and cook for about 45 minutes. Brush with marinade; turn. Continue cooking until an instant-read thermometer inserted into the center reads at least 145 degrees F (63 degrees C), about 1 hour and 15 minutes more. Do not use any more marinade on cooked meat until after you boil it.
Place leftover marinade in a saucepan; bring to a boil; let simmer for 1 minute. Remove from heat. Now you can use it to brush over the cooked pork.