I think I may have done that Singapore food tour last year based on the starting point and dishes offered. After indulging in roti we probably managed to move another 100 meters in 45 minutes and consume nothing more so at that stage, like yourself, we bailed out feeling disappointed. The couple of flights I took with TK left me feeling meh, as I had heard so much hype about their food and service, I was left scratching my head as I felt both were only average at the best and doubt I will bother flying them between Asia and Europe even if they are the cheapest.