What is this Chinese tong sui called?

A few days ago, I saw my parents eat something that looked like a Chinese sweet soup (tong sui). The liquid was black and thin. I saw a brown hard boiled egg (looks like it was dyed with soy sauce or something) in each of their bowls. At first I thought it was pigs feet with ginger and black vinegar (what people eat after they get a baby) but I didn't see any pigs feet. What is this thing my parents ate?|||Don't you think that you might get a more accurate answer to your question if you were to, y'know, ask your parents?|||Like what the first answerer said, shouldn't you ask your parents instead? And I think it's tang sui, sugar water in mandarin unless you're Cantonese or something.