Step 1

If using mushroom powder, stir powder into 2 cups warm water in a small bowl to dissolve. Set mushroom stock aside.

Step 2

Heat oil in a wok or large skillet over medium-high. Cook onion and garlic, stirring often, until translucent and light golden, about 4 minutes. Add celery and carrots and cook, stirring, 1 minute; season with salt and pepper. Add cabbage, mushrooms, and snow peas; cook, stirring occasionally, until crisp-tender, about 3 minutes.

Step 3

Add liquid seasoning, oyster sauce, soy sauce, and reserved mushroom stock (or vegetable broth). Bring to a simmer, add noodles, and cook until liquid is absorbed and noodles are al dente, 8–10 minutes. Season with fish sauce and more salt and pepper if needed.

Step 4

Divide pancit among bowls; top with scallions. Serve with lemon wedges for squeezing over.