Using a fork, stir the egg, 2 tablespoons sweet chili sauce, hoisin sauce & soy together in a large bowl. Add the breadcrumbs, salt & pepper; stir to combine. Let mixture sit for 5 minutes to soften the breadcrumbs.
Line a baking sheet with parchment paper or greased foil. Preheat the oven to 350F (180C).
Add water chestnuts, carrot, onion, ginger, garlic & cilantro to the breadcrumb mixture; stir to combine.
Add beef & pork, stiring thoroughly until everything is combined – I use my hands for this & usually wear surgical gloves (for ease of clean-up & sanitation). Place the mixture on a piece of parchment paper. Press the mixture to form a 10 x 14-inch (25 x 35cm) rectangle. Roll-up from one short side, jellyroll style, to form a log. Place on prepared baking sheet, seam-side down. Bake, uncovered, for 30 minutes.
While the meatloaf is cooking, combine melted butter, 2 tablespoons sweet chili sauce, 2 tablespoons hoisin sauce & 1 tablespoon of soy in a small bowl. Brush some of the mixture over the meatloaf. Cook, brushing with sauce mixture twice more during cooking until it's all used, for 30 minutes or until firm & cooked through when a meat thermometer inserted into the center reads 160F/71C. Cover & let stand 5 to 10 minutes before cutting into about 1-inch (2.5cm) thick slices. Serves 6.