Black Bean Sauce is a thick, salty dark-brown sauce made from fermented soybeans. Black bean sauce, also referred to as paste is used extensively in Asian cooking. The sauce may be flavored with other ingredients such as garlic.
This ingredient is typically easy to find in most well-stocked grocery stores such as Walmart. Many types can be found in most any Asian market.
If you don't have black bean sauce use one of these substitutes: