Pho is the best soup on the planet as far as I'm concerned and it's all about the broth. It is extremely time consuming to make from scratch though. However, it's worth it. Try using a a pressure cooker to greatly reduce the cooking time.

In a large stock pot cover the oxtail, short ribs, and beef bones with cold water. Boil for 20 min. The surface of the water will become murky as the scum from the beef rises to the top. Remove the meat and the bones. Dispose of the water and rinse the stock pot well. Wash all of the meat and bones with cold water to remove the remainder of the impurities.

Refill the stock pot with 16 cups of fresh water, 1/3 cup of fish sauce, 1 tbsp of rock sugar, and place the bones and meat back in. Meanwhile, toast 1 yellow onion (halved), 1 large knob of ginger (halved), and 2 stalks of lemongrass. Once toasted, add to the stock pot and slowly bring to a simmer. Cover and set a timer for 6 hours.

1 hour in, remove the short ribs and set aside to cool and slice for later. Prep the Thai chiles and fresh garlic. Slice thin and allow them to marinate in rice vinegar.

2 hours in, skim the layer of excess fat off the top of the broth and discard.

4 hours in, take the pho spice packet (star anise, cinnamon stick, cloves, coriander, and fennel seeds) and lightly toast until fragrant. Tie the cheesecloth bag tightly with the spices and place into the broth and submerge.

6 hours in, set the oxtail aside with the short ribs for serving. Pitch the beef bones, spice packet, and aromatics. Season the broth to taste with more fish sauce and salt as necessary.

Double-strain the broth through a fine mesh sieve and colander to remove the remaining floating bits of debris. The broth should be a rich dark brown color and super clean.

Prepare the rice noodles by letting them sit in hot (not boiling) water for 8 minutes. The hot broth will finish cooking them.

Serve in ramen bowls over rice noodles with a few slices of short rib, 1 piece of oxtail, fresh cilantro, fresh Thai basil, fresh green onion, a slice of lime, and a couple spoonfuls of the chiles with garlic.