In a large mixing bowl, combine the flour and salt. Slowly add the water while stirring with chopsticks or a fork until shaggy dough pieces form. Knead the dough by hand for about 2 minutes, until it comes together into a mostly smooth ball. Add a bit more water if necessary—the dough should feel moist but not sticky. Cover the dough with plastic wrap and let it rest for 30 minutes.
After resting, knead the dough again for about 1 minute. If it’s not smooth yet, try kneading it for a few more minutes and/or letting it rest a bit longer. Divide the dough into 7–8 pieces, each weighing about 50 grams. Roll each piece lightly into a palm-sized disc and brush both sides with vegetable oil. Stack the discs on a plate, cover with plastic wrap and let them rest for at least 2 hours (at room temperature), or overnight in the refrigerator.
Make the Spicy Beef Stew
Cut the beef into 1-inch (2.5cm) chunks. Soak the pieces in cold water for 15–30 minutes if time allows, then drain the water
Put the beef, 2 slices of ginger and 4 cups of cold water into a pot. Bring the mixture to a boil over medium heat and skim off any foam. Simmer for 10 minutes. Remove the beef and rinse it under cold water, then drain it and pat it dry. Reserve the cooking liquid and strain it to use later as stock.
In a Dutch oven or a heavy-bottomed pot or wok, heat 2 tablespoons of vegetable oil over medium heat. Add the rock sugar and stir it until it caramelizes to a deep amber color. Add the beef chunks and stir-fry them until they are evenly coated with the caramelized sugar. Push the beef to the side of the pot.
Add the doubanjiang and stir-fry for 1–2 minutes, until the red oil releases. Add the garlic, scallion, remaining ginger, star anise, cassia, fennel seeds, bay leaf, Sichuan peppercorns and dried chilies. Stir-fry everything briefly, until the spices become aromatic.
Deglaze the pot with 3 cups of the reserved beef stock. Add the light soy sauce, dark soy sauce and hot pot soup base (if using). Bring the mixture to a simmer.
Cover the pot with a lid and braise the beef over low heat for 1½–2 hours, until the beef is tender. At the 1-hour mark, taste the broth and adjust the seasoning with salt as needed.
Cook and Serve the Noodles—One Bowl at a Time
Bring a large pot of water to a gentle boil (use the largest pot in your kitchen, so you have plenty of room to cook the noodles).
Working with one dough disc at a time, flatten it evenly with a rolling pin, then stretch the dough by pulling its corners outward until it forms a thin, square(ish) sheet about 6 inches (15cm) on either side.
Carefully drop the noodle sheet into the boiling water. Repeat with another disk (but only if there's room in the pot to cook two sheets at a time). Boil the noodle sheet(s) for 2–3 minutes. Remove the sheet(s) with a slotted spoon and set into a serving bowl. Ladle up to ⅓ of the beef topping onto the noodles and garnish with fresh cilantro.
Repeat with the remaining dough discs, topping and garnish, to make 3 bowls of noodles.
Notes
While the noodle ingredients above are listed by volume to accommodate cooks without scales, the noodles will be best if the ingredients are weighed, so that you can be sure to have a 2:1 ratio of flour to water.