Chop the beef into ⅘cm pieces, add salt and vinegar then mix. Cover with water and set aside.
Slice the spring onions and red onion, smash the garlic and ginger then slice. Slice the white parts of the spring onion and thinly slice the green parts. Chop the tomatoes into small pieces.
Toast your spice mix in a dry pot until aromatic, then place them in a tied spice bag.
To a large pot, add 2 tbsp of vegetable oil on medium heat, along with the ginger, garlic and red onion. Fry for a minute or two until fragrant then add the spring onions, tomatoes, chilli flakes and sugar.
Rinse the beef and when the water turns clear, it's ready for braising. Add the beef to the pot, fry untouched for a minute or so, then add the bag of toasted spices and 1.2L water.
Simmer for two hours, remove the bag of spices, beef and all the vegetables from earlier.
Add the remaining seasonings and sauces to the pot along with the braised beef and simmer for an extra 20 minutes or until the beef is as tender as you like.
Remove the beef again, and add the pak choy for just 20-30 seconds.
Place fresh noodles in bowls, top with braised beef, pak choy, and spring onion greens. Ladle over the broth and enjoy.
