Make the dough: Mix 280 grams of water with 480 grams of bread flour to form a rough ball. Cover and autolyze in a cool place for 45 minutes.
Add yeast, salt, and honey: Cut dough into pieces for easier mixing. Add 10 grams salt, 25 grams honey, and 5 grams active dry yeast dissolved in 5 grams water. Knead until combined and dough is no longer sticky.
Knead dough: Knead dough by slapping it against the work surface about 150 times or until it passes the windowpane test (stretch into thin film without tearing). Alternatively, use a stand mixer at high speed (around 5) to mimic this.
Divide and shape dough balls: Divide dough into portions for 8 bagels (4 flavors). For unstuffed bagels, shape dough into smooth balls by pinching edges to center and placing seam side down. Rest for 20 minutes.
Prepare cheese stuffing: For triple cheese bagels, knead 8 grams shredded parmesan into dough until cheese is incorporated. Shape into balls and rest 20 minutes.
Roll out dough and add fillings: Roll each dough ball into a rectangle about 15 cm wide and 18-20 cm long. For cheese bagels, place 8 grams cubed cheddar along one edge, leaving 2 cm margin. Roll into a log and pinch closed. Rest seam side down for 10 minutes.
Prepare red braised pork filling: In a small pan over low heat, fry 0.5 tablespoon sugar with 2 teaspoons oil until sugar melts. Add 70 grams pork belly cubes, 0.5 cm ginger slices, and white parts of 2 scallions. Fry until browned (~4-5 minutes). Add 3/4 cup hot water, 1/4 tsp Shaoxing wine, 1/2 tsp soy sauce, 1/4 tsp dark soy sauce, and 1/4 tsp five spice powder. Simmer on low until sauce reduces to 2-3 tablespoons (~15 minutes). Season with 1/8 tsp salt and 1/8 tsp MSG. Thicken with slurry of 1/2 tsp cornstarch. Cool before stuffing.
Prepare sweet purple potato filling: Steam 70 grams purple sweet potato with 1 tablespoon water for 4 minutes until soft. Mash with 4 grams sugar, 6 grams melted butter, and 10 grams sweetened condensed milk. Use as stuffing.
Stuff bagels with pork or sweet potato filling: Stuff dough logs with prepared fillings similarly to cheese. Pinch sides closed tightly to avoid leakage.
Final shaping: Roll each log to 20-25 cm length. With seam side down, press one end to form a fish tail shape, then wrap the other end around and pinch closed, hiding the seam underneath.
Proof bagels: Let shaped bagels proof covered for 60 minutes.
Boil bagels: Bring 1 liter water to rapid boil, add 1 tablespoon granulated sugar, reduce to gentle simmer. Boil bagels 30 seconds per side. Drain on cloth.
Bake bagels: Place boiled bagels on parchment paper, optionally add toppings. Bake in preheated 200°C oven for 15 minutes.
Add finishing cheese slice (optional): For triple cheese bagels, place a slice of American cheese on hot bagels immediately after baking. Let cool before serving.