1. Heat a gas grill or grill pan to high. Cook onion and ginger, turning occasionally, until charred on 2 sides, 15–20 minutes.
2. Alternately, adjust oven rack to highest position and heat broiler to high. Place onion and ginger on a foil-lined baking sheet and cook, turning occasionally, until charred.
3. Heat a large stockpot over medium-high heat. Add cloves, star anise, cinnamon sticks, coriander seeds, and fennel seeds to pot. Cook, stirring continuously, until fragrant and toasted, about 1 minute. Add broth, water, fish sauce or coconut aminos, and sugar; stir to combine well. Add charred onion and ginger. Bring to a simmer and let gently simmer for 30 minutes.
4. Strain broth through a finemesh sieve and return to pot, discarding solids. You should have about 10 cups. Taste broth and adjust seasonings as needed (more fish sauce, coconut aminos, sugar, or salt) to make it tasty enough to drink.
5. While broth simmers, cook noodles according to package instructions and prepare desired toppings.
6. To serve, place noodles and toppings into each bowl. Pour hot broth over top and enjoy!
NOTE: Pho is only as good as the broth! I prefer using a pre-made broth to save on time and create a richer flavor.