Soak the rice sticks in warm water for 15 minutes. Drain, rinse, and soak in warm water for at least another 45 minutes. You can continue to soak the noodles for up to 4 hours -- just replace the water every hour.
Saute the star anise, ginger, onion, star anise, cinnamon stick, and cloves in the pressure cooker over medium heat for 5 - 7 minutes.
Add the oxtail, salt, and sugar. Fill the pot with water up to the max line. Pressure cook on high for 40 minutes. Allow pressure to naturally decrease, about 20 minutes.
Strain the broth. Place the oxtail in a bowl, and discard the remaining solids. Skim the fat from the broth. Add fish sauce and more sugar to taste.
Fill a medium pot with water and bring to boil. Add the noodles and cook for 30 to 60 seconds, or until soft. Drain and rinse with cold water to prevent them from sticking. Place noodles and a piece of oxtail in a large bowl, and top with herbs and peppers. Cover with broth. Add lime juice, fish sauce, sriracha, and hoisin to taste.