In a measuring cup, add vinegar, soy sauce, sugar, mustard, salt, and sesame oil. Whisk in olive oil little-by-little until the sauce is combined and emulsified.
Prep:
Slice the deli meat to short strips, whisk the eggs in a small bowl, remove the chili pepper seeds and slice into thin strips (if using).
Saute:
Mushrooms: In a medium saute pan, add the mushrooms and spread out into a single layer. Cook over medium heat without disturbing until the mushrooms sweat, 5 minutes. Add 1 tbsp oil. Flip to cook further until browned, 4-5 minutes. Transfer out and set aside.
Eggs: Use the same pan, add 0.5 tbsp oil. Pour in the eggs and quickly swirl it around to make into a round and flat shape. Once the eggs are firm enough to flip, cook for 30 more seconds. Transfer it out and slice into short thin strips.
Soak glass noodles:
In a medium heatproof bowl, add the dry cellophane noodles and pour boiling hot water over until about 0.5 inch water level above the noodles. Soak for 4 to 5 minutes (toss the noodles about 3 minutes into soaking. The noodles will turn from opaque to transparent. Don’t over soak them because they will continue to soften and turn mushy.
Drain the noodles over a colander and quickly rinse under cold tap water. Shake away any excess liquid. Add them directly into a large serving salad bowl.
Zucchini:
While the noodles are soaking, shave the zucchini, using a vegetable peeler, into long ribbons. Set aside.
Combine:
Add the noodles, deli meat, eggs, chili pepper, mushrooms, and zucchini into a large serving salad bowl. Pour over the dressing and toss. The zucchini ribbons will soften as you toss but still remain crisp for texture. Garnish with toasted sesame seeds. Serve immediately.
Notes
Glass noodles and cellophane noodles are the same thing. They’re also called bean thread noodles, mung bean noodles, or Chinese vermicelli. Made from mung bean starch, they’re different from rice vermicelli (made from rice flour) and Korean glass noodles (made from sweet potato starch), so don’t mix them up!
Glass noodles: Don’t over soak the noodles. They will continue to soften (if sitting in the water for too long) and turn mushy and sticky. The noodles should look transparent, soft, silky but still with some bites to them.
To prevent glass noodles from sticking, you can also toss the noodles with a bit of oil to prevent them from sticking after they are softened.
Make-ahead: You can make the dressing up to a week in advance. Slice the ham and chili pepper, cook the egg ribbons, and sauté the mushrooms a day ahead—just store them separately in the fridge. On the day of serving, soak the cellophane noodles, combine everything, and serve!
Storage: Once softened, the noodles don’t store well. They harden in the fridge, and since this is a salad, it doesn’t reheat well. It’s best to make just enough for the day and only toss the noodles with the dressing right before serving.