For congee, I gave up .. I tried to put pork, chicken, dried scallop, salt or soya saurce. She still refused to eat.
For cereal, after I add some apple puvree or veg or egg yolk, she is okay. Then, I tried different brand e.g. Heinz, Nestle, Gerber, Earth Best and "Man Chiu" (a korean brand) .
don't do this ! once you start, they will never focus on eating. even don't play with them when you are feeding. you must have patience.
among all my friends' babies, my girl is the only one that can sit at the table and eat with the adults for 1-2hours. other babies cannot stay for more than 5 mins and then running around the restaurant.