Whisk the eggs. In a small bowl, beat the eggs until smooth. If you like silkier ribbons, whisk in the cornstarch. Set aside.
Build the broth. In a medium pot, add the broth, water, ginger, garlic, soy sauce, and the white parts of the green onions.
Bring to a steady simmer over medium heat.
Add veggies if using. If you’re adding mushrooms, corn, or firm veggies, stir them in now so they can soften while the broth simmers for 2–3 minutes.
Cook the ramen. Add the ramen noodles and cook according to package directions, usually 2–3 minutes, until just tender. Stir gently to separate the strands.
Create a gentle swirl. Lower the heat so the soup is at a light simmer, not a rolling boil. Use a spoon to stir the broth in one direction and create a slow whirlpool.
Stream in the eggs. While the broth is swirling, slowly drizzle in the beaten eggs in a thin stream.
Let them set for about 30 seconds, then gently stir to form delicate ribbons.
Finish and season. Turn off the heat. Stir in the sesame oil, vinegar (if using), and chili crisp or red pepper. Add the green onion tops and any tender greens like spinach; they’ll wilt from the residual heat.
Taste and adjust with more soy sauce, salt, or pepper.
Serve hot. Ladle into bowls and enjoy immediately while the noodles are bouncy and the egg ribbons are tender.