Alison Herman TV Critic In the spring of 2023, Hong Kong had just opened up to tourism after three years of pandemic-related restrictions. So for the third season of his PBS travel show “Field Trip,” Australian-born chef Curtis Stone assembled a supersized episode highlighting the coastal, cosmopolitan city’s culture and cuisine, from martial arts to seaside seafood stalls. Stone had visited Hong Kong previously, but the “Field Trip” spotlight is a more in-depth look at a unique location that most travelers haven’t been able to experience since late 2019.