Ex Chef here and a Vietnamese that has ran restaurants for most of his life. I have a few questions: How did you render that broth? What was the seasonings? I ask because I see tell tale signs that its either skimmed or something is off. Color is acceptable (it varies) and was the heat boiling or simmering (different taste outcome, ever slightly. If simmer it'll be sweeter. If boiled it'll break down too much and have bad effect. Did you include tendons and bones to fortify the broth? Please never use vermicelli, use rice noodles (white only) must blanch them as the glutten process is from fermentation, so sometimes theres a sour taste. Also, you might be a person that doesn't like greens but most of Vietnamese food is accompanied not as a side dish but as an inclusion, you have heavy food with is broth and meat, must balance out with veg or green. You'll feel less or no lethargy after eating. But then if you eat too much it'll be same outcome. Good stuff for trying. Broth is normally 4-8 hours to make. In culinqry school my Head Chef hated my gut so he gave me my own countrys dish and told me to make it in 45 minutes. Accomplished with some equipment to make it happen. So in a way it doesn't have to be 4-6 hours. But you can taste the difference in collagen and other tastes that rounds it out. Keep in mind Vietnanese are very anal about their cooking, and they will tell you if you suck. As they still want to eat what you make, just better.