Prepare the noodles according to the package directions; drain and set aside.
In a wok or large skillet, heat the oil and add the onion, garlic, and ginger; stir fry until the onion is limp.
Stir in the leeks or scallions, snow peas, and bean sprouts, and cook until tender-crisp.
Then stir in the noodles, kecap manis, and sambal or cayenne.
Add the eggs or tofu.
Mix throughly until heated through (about 5 minutes).
Serve hot.