For the broth:
1 large onion, peeled and halved
2-inch piece fresh ginger, peeled and halved lengthwise
3-inch cinnamon stick, preferably Vietnamese cassia-cinnamon
1 star anise
2 whole cloves
1 teaspoon coriander seeds
4 cups unsalted vegetable stock or broth
2 teaspoons soy sauce
4 carrots, peeled and coarsely chopped
For the noodles:
1/2 pound dried flat rice noodles (known as bánh phở; use 1/16", 1/8", or 1/4" width depending on availability and preference)
For the toppings (choose a few):
Protein such as fried or baked tofu, bean curd skin, or seitan
Mushrooms
Vegetables such as bok choy, napa cabbage, or broccoli
For the garnishes (choose a few):
1/2 large onion, very thinly sliced
2 scallions, thinly sliced
1 chile pepper (Thai bird, serrano, or jalapeño), sliced
1 lime, cut into wedges
1/2 cup bean sprouts
Large handful of herbs: cilantro, Thai basil, cilantro
Hoisin sauce, Sriracha (optional)
To make the broth, char the onion and ginger over an open flame (holding with tongs) or directly under a broiler until slightly blackened, about 5 minutes on each side. Rinse with water.
In a large pot, dry-roast cinnamon, star anise, cloves, and coriander over medium-low heat, stirring to prevent burning. When you can smell the aroma of the roasted spices, add vegetable stock, soy sauce, carrots, and charred onion and ginger.
Bring broth to a boil, reduce heat, and simmer, covered, for 30 minutes. Strain and keep hot until ready to serve.
Make the noodles while the broth simmers. Place the noodles in a large bowl and cover with hot water. Let stand for 20 to 30 minutes or until tender but still chewy. Drain. (If soaking does not soften the noodles enough, blanch them in a pot of boiling water for a few seconds.)
Prepare the toppings as desired – slice and cook tofu, lightly steam or blanch vegetables, and so on. Toppings should be unseasoned or only lightly seasoned so as not to interfere with the flavor of the broth.
To serve, divide the noodles between two bowls. Arrange toppings over noodles. Ladle the broth between the two bowls. Serve with garnishes on the side, which diners should add to taste.
This recipe has been updated — first published January 2010.