In large grocery stores, you'll find commercially made Shanghai noodles made with egg whites; however the artisanal noodles are made with yolks. The difference is evident in the color of the uncooked noodles. 

These thick noodles are also available in a thin version. 

Cooked noodles are usually labelled "with oil" and contain canola oil or other vegetable oil, therefore it's important to read the label. 

No preparation required.

Cook for 4 or 5 minutes in boiling water. Drain, rinse well. Prepare according to your recipe. Keep in mind they soak up sauces and broths, so don't skimp!

They are most often used in Chinese stir fries or soups.

They are traditionally used in the pork dishes with dark soy sauce that are so popular in China.