Heat the broth (if making it from cubes, simply mix the cubes with boiling water in a glass measuring cup or bowl). Add the eggs and stir until the yolks break and cook (more or less dissolve) in the broth. Stir in the fish sauce, vegetarian fish sauce, or soy sauce. Set aside.
For more formal occasions: Scramble the eggs separately, and set aside until noodles are done, then add them (this makes for "neater" looking noodles). If Using Tofu: Stir the soft tofu into the broth as you would with eggs.
Place a wok or large frying (it should be quite deep) over medium-high heat. Add 1-2 Tbsp. oil and swirl around, then add the garlic, chili, and cooking onion. Stir-fry 1 minute, or until fragrant. Whenever the wok/frying pan becomes dry, add a Tbsp. of wine/sherry or broth instead of more oil. This will save you added calories and fat.
Add the mushrooms and continue stir-frying another 2 minutes, or until mushrooms have softened.
Add the "whiter" pieces of bok choy and stir-fry another minute or two, until softened.
Now add the broth-egg (or broth-tofu) mixture you made earlier, plus the bok choy greens, stirring to combine.
When this soup-like mixture starts to bubble, reduce heat to medium and add the noodles. Don't worry if the noodles (which are usually dried in square or rectangular shapes) look as if they're just "floating" on top. Using your spoon or spatula, press them down into the broth, then gently turn them over and do the same with the other side. Gradually they will soften down into the hot liquid and separate.
As the noodles soften, continue to turn and mix them over medium heat using a tossing motion (almost as if you were tossing a salad) until all the broth has been absorbed. Do this gently , as the noodles are very thin and tear easily.
When all the broth has been absorbed (after about 5 minutes), turn off the heat and add the bean sprouts and sprinkle over the black or white pepper. Again, "toss" the noodles to mix these ingredients in.
Taste-test the noodles. If they need more salt, sprinkle 1 more Tbsp. fish sauce, vegetarian fish sauce, or soy sauce over noodles and toss to combine. Do this until desired taste is achieved. If too salty for your taste, squeeze 1-2 Tbsp. fresh lime or lemon juice over noodles and toss to combine. Note: the saltiness of your noodles will depend on how salty your broth was to start with, so you may have to adjust accordingly.
To serve: portion out the noodles onto individual plates and top each with a sprinkling of coriander plus a wedge of fresh lime. OR, heap all the noodles onto a large serving platter. Sprinkle with fresh coriander and add lime wedges around the sides. If desired, serve with Thai chili sauce on the side, and ENJOY!
