Add the onions, ginger, garlic, cinnamon sticks, coriander seeds, beef broth, coconut aminos or soy sauce, and fish sauce to a large stockpot, then bring the mixture to a boil over medium-high heat. Lower the heat to medium-low, cover, and let the broth simmer for 30 minutes until the kitchen smells warmly spiced.

Place the sirloin on a plate, cover it with plastic wrap, and chill it in the freezer for 15 minutes while the broth infuses. The beef should feel firmer around the edges but should not be frozen solid.

Slice the chilled sirloin very thinly across the grain with a sharp knife, then cover and refrigerate it until assembly. Aim for slices no thicker than 1/4-inch so the heat from the broth can reach them quickly.

Set the shirataki noodles in a colander and rinse them thoroughly with warm water. The noodles should smell clean and feel less slick once the packaging liquid has rinsed away.

Strain the broth through a sieve, discard the solids, and return the clear broth to the pot over low heat. Keep it very hot and steaming, just below a simmer, with no whole spices or aromatic chunks left behind.

Divide the rinsed shirataki noodles among 4 serving bowls and arrange several raw beef slices in a single layer over each portion. Leaving space between the slices helps the hot broth reach the meat evenly.

Ladle the steaming broth directly over the beef and noodles. The beef should shift from translucent red to opaque pinkish-brown as the broth hits it.

Finish each bowl with scallions and cilantro, then squeeze 1 quarter lime into each serving and offer hot sriracha sauce, if using. The lime should brighten the savory broth, while the herbs stay fresh and fragrant on top.