Hot and sour soup is a dish that lives or dies on the balance of two ingredients: white pepper for the heat and Chinkiang black vinegar for the sour. Most American restaurants substitute cayenne and rice vinegar. Most American restaurants serve a worse soup.
Darren Sayphraraj runs We Have Noodles in Los Angeles' Silver Lake. He came to Bobby's kitchen in 2017 with the actual ingredients, in the actual proportions, and that was most of the game. The remaining structure — silken tofu cut into batons, dried wood-ear mushrooms rehydrated and slivered, bamboo shoots, a slurry of cornstarch added in two stages, an egg drop ribboned through at the very end with the heat off — is timing.
Bobby has lost to Chinese cuisine many times in this ledger. Pantry has cost him more than skill ever did.