Break up large clumps of rice with a fork. Heat 2 tbsp. vegetable oil in a wok or large frying pan (not nonstick) over medium-high heat. Add onion, ginger, garlic, and sausages and cook, stirring constantly, until fragrant, about 30 seconds. Add rice and cook, stirring often, until each grain of rice is dry and fluffy, 2 to 3 minutes. Add asparagus and cook until bright green, about 1 minute.
Push rice to outsides of wok to create a well in the center. Add remaining 2 tsp. vegetable oil. Pour eggs into well and cook, stirring occasionally, until large curds form and eggs are fully cooked, about 2 minutes.
Add salt, white pepper, and sesame oil and toss rice until all ingredients are well combined. Sprinkle with green onion and serve with soy sauce if you like.
*Find Chinese sausages at East Asian markets.