Bring a medium pot of water to boil. Add the noodles and cook for 1 minute less than package directions; the noodles should retain a slight chew and not be fully cooked. Using a colander, drain immediately and rinse with cold running water to stop the cooking process. Shake the colander well, allowing any excess water to drip off.
In a large bowl, toss noodles with 2 tablespoons kecap manis along with soy sauce to evenly coat.
In a large wok or nonstick skillet, heat oil over medium heat until shimmering. Add the shallot and garlic, and cook, stirring constantly, until fragrant, 15 to 30 seconds.
Increase heat to medium-high and add the carrot, onion, salt, and pepper. Stir frequently, and cook until onion is translucent, about 3 minutes. Add the cabbage, and stir-fry until tender, 2 to 4 minutes.
Add seasoned noodles and cook, tossing frequently, until heated through, 2 to 3 minutes. Taste and add 1 tablespoon kecap manis, if desired. Add scallions and stir through.
For Serving: Divide noodles among 2 plates and sprinkle with fried shallots. Serve hot with acar timun, sambal, and shrimp crackers, if desired.
