Peel and slice the ginger into 6–8 coins. Lightly crush each slice with the flat side of a knife. Thinly slice the green parts of the green onions to yield ¼ cup and set aside for garnish. Cut the remaining onion stalks into 3-inch sections and crush lightly.

In a 4-quart pot, toast the star anise, cinnamon stick, and cloves over medium heat for 1–2 minutes until fragrant. Add the crushed ginger and green onion sections, stirring briefly to release their aroma. Remove the pot from the heat for about 15 seconds, then pour in both the beef and chicken broths.

Return the pot to medium-high heat, add the water and salt, and bring to a gentle boil. Reduce the heat and let the broth simmer uncovered for 30 minutes to infuse the flavors.

After simmering, strain the broth through a fine-mesh sieve into a clean 3-quart pot, discarding the solids. Adjust the volume to approximately 8 cups by adding water or reducing slightly if necessary. Stir in the fish sauce and sugar (or maple syrup, if using). Keep the broth warm over medium heat.

In a large pot, bring water to a rolling boil. Add the rice noodles and cook for 5–7 minutes, or until tender yet slightly chewy. Drain the noodles and rinse under cold water to remove excess starch. Allow them to drain completely before dividing evenly among four serving bowls.

In a bowl, combine the sliced beef with black pepper, sugar, cornstarch, fish sauce, and soy sauce. Mix thoroughly and let rest for several minutes. Arrange the prepared garlic, onions, cilantro, and green onion tops near the cooking area for convenience.

Heat a large nonstick skillet over medium-high heat. Add 2 tablespoons of oil, followed by the garlic and onion. Sauté until fragrant, about 30 seconds. Push the aromatics to one side, increase heat to high, and add the beef in a single layer. Allow it to cook undisturbed for 1 minute, then stir and cook for another 1–2 minutes, until the beef is lightly browned yet slightly rare in the center.

Distribute the cooked beef evenly among the prepared noodle bowls. Add the sautéed onions and garlic. Garnish with chopped cilantro and sliced green onions.

Taste the broth once more and adjust seasoning as desired. Bring the broth to a quick boil, then ladle it generously over each bowl, covering the noodles and beef.

Serve immediately with optional garnishes such as bean sprouts, basil, mint, sliced chiles, hoisin sauce, lime wedges, and sriracha. Encourage guests to season their bowls to taste.