To prepare the eggs, in a bowl, crack the eggs and season with the salt, then whisk until smooth. In a nonstick pan over medium heat, add 1 teaspoon of cooking oil. Pour in half of the egg mixture and cook both sides until set, about 2 minutes total. Repeat with the remaining egg mixture and cooking oil. Once cooled, slice the cooked eggs into thin strips.
To blanch the noodles and vegetables, in a pot of boiling water, blanch the glass noodles for 30 seconds, then drain. In the same pot, blanch the carrots for 20 seconds, then drain. Finally, blanch the spinach for 10 seconds, then drain and gently squeeze out the excess water.
To make the sauce, in a small bowl, whisk together the soy sauce, Chinkiang vinegar, and sugar until dissolved.
To assemble the glass noodle salad, in a large mixing bowl, combine the glass noodles, spinach, carrots, egg strips, scallions, garlic, hot peppers, and chili flakes.
To finish the glass noodle salad, in a small pan over high heat, heat the cooking oil until smoking hot. Carefully pour the hot oil over the garlic, scallions, and chilies, if using, to release their fragrance. Drizzle the prepared sauce over everything and toss well to coat. Serve immediately or chilled.