Why did he say "Congratulations" in here? Is it used ironically?
Native speaker’s answer
Rebecca
Yes, he is using "congratulations" sarcastically here. He sarcastically says "congratulations" because he is frustrated that San Francisco has "ruined pizza" by putting broccoli on it. Therefore, instead of saying something like "congratulations, San Francisco has the best pizza" (which would be using "congratulations" in a serious way), he "congratulates" San Francisco on "ruining pizza".