Put noodles in a large bowl and cover with boiling water. Let sit 5 to 8 minutes, or until tender. Drain; rinse with cold water.
Heat a large wok over medium heat. Add oil and swirl to coat. Add garlic and cook until fragrant, 30 seconds. Stir in sambal (start with 1 tbsp.); mixture will spatter, so stand back after adding.
Increase heat to medium-high and add sausages. Cook, stirring occasionally, until sausages are light golden, 1 to 2 minutes. Add onions and cook, stirring, until beginning to soften but still quite crisp, 1 to 2 minutes. Add noodles and soy sauce, stirring to coat.
Make a well in pan. Crack in eggs (push noodles aside if they fall into the center) and cook until whites begin to set, 3 minutes. Break yolks with a spoon; scramble eggs and toss with noodles.
Add white pepper, 1 tbsp. water, the bean sprouts, and crab; cook, stirring, until bean sprouts are tender-crisp, 2 minutes.
*We love the complex flavor of Glory brand's Nonya Sambal Chilli, available at Asian grocery stores. Grind white pepper in a clean coffee grinder; its fresh taste is worth the effort.
Note: Nutritional analysis is per serving.