Step 1: Prepare the Suet. Thoroughly rinse the beef suet under cold water and pat it completely dry with paper towels. This removes impurities.
Step 2: Cut the Suet. Cut the suet into small, uniform pieces (1/2 to 1 inch cubes) or grind it using a meat grinder. Smaller pieces render faster and more evenly.
Step 3: Begin the Rendering Process. Place the cut or ground suet into a large, heavy-bottomed pot or Dutch oven. Add 1/2 to 1 cup of water to the pot, just enough to cover the bottom and prevent sticking.
Step 4: Slow Cook. Heat the pot over very low heat. Slowly melt the fat without browning. Stir occasionally. The water will evaporate as the fat melts and separates from connective tissues. This can take 2-4 hours, or longer.
Step 5: Monitor and Strain. Continue cooking until all fat has melted, and solids (‘cracklings’) are golden brown and crispy. The liquid tallow should be clear. Remove from heat.
Step 6: Filter the Tallow. Place a fine-mesh sieve lined with several layers of cheesecloth or a coffee filter over a heat-proof bowl. Carefully pour the hot liquid tallow through to remove all solids. Repeat if necessary for purity.
Step 7: Store Properly. Allow the filtered tallow to cool completely at room temperature until it solidifies into a creamy white, firm consistency. Transfer to clean, airtight jars and store in the refrigerator for several months or freezer for up to a year.