Gather beef fat (suet or trim)
Cut the fat into small pieces
Remove any meat, blood, or gristle
Place the fat in a heavy pot or slow cooker
Heat on low until the fat melts
Stir occasionally to prevent sticking
Continue cooking until the solid bits turn golden and crisp
Strain the liquid fat through a fine mesh strainer or cheesecloth
Pour the strained fat into clean jars or containers
Let it cool until solid
Store in a cool, dark place or refrigerate