Make the Sauce
Whisk all ingredients together in a small bowl and set aside.
Warm the Noodles
If you’re using fresh noodles, place them in a microwave-safe bowl, cover them with a slightly damp paper towel, and microwave for 2 minutes. They should feel very flexible once you pull them out. Separate the noodles into a bowl and set aside.
Make the Noodles
Whisk together eggs and soy sauce in a small bowl and set aside. In another bowl, mix the chicken with cornstarch until all the pieces are coated. Set aside.
Heat a large wok or skillet over medium-high heat. Add the oil and garlic, stirring constantly for 30 seconds until the garlic is barely golden brown. Don’t walk away because garlic burns quickly! Once the garlic is just turning golden brown, add chicken and use a wooden spoon to distribute chicken in an even layer over the bottom of the pan. Cook, stirring frequently, until the chicken is golden brown, 3 to 5 minutes.
Lower the heat slightly and move the chicken and garlic to one side of the pan. On the exposed side, pour in the egg and soy sauce mixture. Allow the eggs to cook for 2 to 3 minutes until set, then break up the eggs into pieces with a spoon, and stir everything back together. Add the onion, bell pepper, jalapeño (if using), and the white and light green parts of the scallions. Cook until the veggies start to soften, 2 to 3 minutes. Add noodles to the pan with the sauce, Thai basil, dark green parts of the scallions, and bamboo shoots. Cook, stirring occasionally, until the noodles have absorbed all the sauce, about 2 more minutes. Serve immediately.