Bring a large pot of water to a boil and salt it. In a smaller pot, bring 6 cups of water to a boil; once boiling, reduce heat so water bubbles gently.
To the smaller pot add soy sauce, ketchup, vinegar, sesame oil, if using, and sriracha or chile
, along with a pinch of salt. Stir and let simmer
Add egg noodles to large pot. Cook's Note: Fresh noodles will be ready in just a couple of minutes; dried will take longer.
When tender, but not mushy, drain
. Taste broth and add more soy, salt, vinegar, or heat as you like. Divide the noodles into bowls and pour hot broth