Bring a pot of water to a boil in order to cook the noodles.

Heat oil in a large skillet over medium high heat until warm. Add green onion and stir a few times until fragrant. Add tomato and stir and chop until it almost becomes a paste, 3 to 5 minutes.

Transfer the tomato paste to a large pot. Add pork stock (or chicken stock or water) and bring to a boil over over medium high heat. Turn to low heat, cover, and let simmer.

While simmering the broth, cook the noodles according to the instructions.

Five minutes before noodles are done, add pork ribs (or whatever leftover meat you’re using) and a spoonful of gravy to the noodle soup. Stir a few times until the gravy is mixed well with the broth. Taste the broth and add more salt if necessary. The broth should taste slightly salty by itself. Add eggs. Cover and simmer for another 2 to 3 minutes, until the eggs are half cooked (or longer if you like them to be fully cooked).

Drain the noodles and divide them among 3 large bowls. Top the noodles with bok choy (optional). Pour the tomato broth over the bok choy so that the hot broth quickly cooks it (be careful not to break the egg yolks!). Transfer an egg and a couple of pork ribs to each bowl.

Serve immediately.