Wash the tomatoes and cut them into small dice; julienne the cucumber into thin strips. Chop the cilantro and chili into short segments — go with 2 chilis if you love heat, 1 or none if you don't.

Insert your fingers into the middle of each king oyster mushroom and tear it apart lengthwise into rough strips — this ragged texture catches sauce better than clean cuts. Heat a little oil in a pan and fry the mushroom strips until golden brown, seasoning with a pinch of salt. The salt seasons the mushrooms and coaxes out moisture, killing any earthy mushroom smell and turning it into pure umami.

Add a little more oil to the pan and stir-fry the diced tomatoes until soft. Stir in the tomato paste for a thicker, richer flavor, then remove the mixture from the pan and set aside. No tomato paste? Tomato purée or mashed fresh tomatoes work just as well.

Bring a pot of salted water to a boil and cook the angel hair pasta for just 2-3 minutes — do not overcook. Drain, then immediately plunge the noodles into a bowl of ice water so they turn cold and irresistibly Q彈 (chewy-bouncy).

Squeeze the juice from the lemon. In a large bowl, combine the chilled noodles with the tomato-mushroom mixture, cilantro, cucumber, and chili. Season with soy sauce, mirin, vegan fish sauce, sesame oil, and the fresh lemon juice; toss well and serve immediately.