When sourcing from manufacturers, prioritize leaf tenderness and uniformity; leaves should be young, thin, and free of tough veins. The filling-to-leaf ratio is critical, typically requiring a tight, machine or hand-rolled seal that prevents bursting during sterilization. Ensure the rice is parboiled correctly to avoid a mushy texture, and verify that the brine or oil medium uses high-quality ingredients like extra virgin olive oil and natural lemon juice rather than citric acid for a premium flavor profile.