In a small bowl, combine the chile powder, five-spice powder, brown sugar, 2 teaspoons salt, and 1 teaspoon pepper. Sprinkle generously all over the ribs. Cover and refrigerate for at least 2 hours but preferably overnight.

Prepare a gas grill for direct grilling over medium-high heat. Grill the ribs until all sides are nicely browned, 1 to 2 minutes per side. Let cool briefly and then tie with a couple of loops of butcher's twine.

Prepare the grill for indirect grilling. Set an 8-quart heavy-duty pot over medium heat and when hot, add the oil. Add the onions and cook, stirring occasionally, until soft, about 5 minutes. Add the garlic and ginger and stir for 1 minute more. Pour in the chicken broth, 1/4 cup of the vinegar, 1 tablespoon of the brown sugar, the fish sauce, and the soy sauce. Add the star anise, bring to a boil, and then remove from the heat.

Put the ribs in the pot and set the pot on the grill over the cool zone. Cover the pot, close the grill lid, and cook for 30 minutes. Check the ribs and rearrange so they remain submerged in the simmering liquid. Check the ribs again after 30 minutes and move them around if necessary. After another 30 minutes, check the ribs for tenderness. They should be fork-tender but not falling apart. If they're not tender enough, continue to cook, checking every 15 minutes. Remove the ribs from the pot and set aside.

Pour the liquid into a heatproof vessel, such as a Pyrex measuring cup, and let sit until the fat rises to the top. Skim off and discard the fat. Taste the liquid; if it's too watery, return to the pot and boil over high heat until flavorful.

Prepare the grill for direct grilling over medium-high heat. Pour 1 cup of the braising liquid into a small saucepan and stir in the remaining 2 tablespoons brown sugar and 2 teaspoons rice vinegar. Over medium-high heat, reduce the liquid until it becomes syrupy, about 12 minutes--you'll have about 1/3 cup.

Brush the glaze over one side of each short rib and grill glazed side down until the glaze begins to bubble and lightly darken, 2 to 3 minutes. Brush another surface with the glaze and turn the ribs. Continue to brush and glaze, turning frequently, until all sides are nicely glazed. Transfer the ribs to a warm platter, drizzle with the remaining braising liquid, and garnish with the scallions and cilantro.

Make Ahead: You can make this dish through the braising step the day before serving. Just cool and wrap the meat and braising liquid separately. Refrigerate overnight and glaze the next day. To spread out the work even more, you can season the meat the day before you braise.

To use a charcoal grill: First build a medium-high fire for searing: Ignite about 5 quarts of charcoal (80 to 100 briquettes), using either a chimney starter or an electric starter. When the charcoal is burning well, spread it out over the surface of the charcoal grate and put the cooking grate in place. Let the charcoal burn down until it's coated with gray ash. To test the temperature, hold your hand about two inches above the cooking grate; when you can hold your hand there for 2 to 3 seconds (a medium-high fire), you're ready to sear the short ribs.

After searing, divide the coals evenly, banking them against two sides of the grill (use long-handled tongs to move the coals). Put the cooking grate in place; if your cooking grate has hinged sections, position them over the charcoal. Place an oven thermometer on the grate over the cooler area, close the lid, and let the coals burn until the thermometer reads about 350 degrees F. When ready, place the pot over the cool zone and braise as directed above. Check the thermometer every 20 minutes, replenishing the charcoal as necessary to keep the temperature between 325 degrees F and 375 degrees F. If the coals are still burning well, you can simply add a handful of unlit coals on top. Otherwise, you'll need to add lit coals.

To glaze the ribs, rebuild a medium-high fire as you did for the searing step, and cook as directed in the recipe.