This is the ultimate way to prepare your schmaltz. Schmaltz is to Jews as bacon grease is to Southerners! Used in many traditional Jewish recipes to replace butter, which is "trayf" (butter is not to be served alongside meat products according to Jewish dietary laws). Try it, you will find it so tasty in many of your savory recipes, you may want to use it all the time.
Chop the frozen pieces of fat coursely, then put them in a skillet with enough water to barely cover. Place over low heat. The fat will start rendering when the water simmers.
When the fat appears about half rendered and the water has evaporated, add the onion, continue to cook until the crackling and onion are well browned.
Pour the fat through a strainer into a jar. It will keep in fridge for months. Save the onions and crackling to flavor dishes, or, since you are so AWESOME, sprinkle with a little salt and eat them before anyone finds out you have them.