With a sharp cleaver or knife, cut pork fat into 1.5 cm (¾-in) cubes. Try to make them as evenly sized as possible.
Combine pork fat with water in a well-seasoned wok or large non-stick pot. Stir and fry slowly over medium-low heat. As it boils, the water will help the lard start to render. Keep frying until the cubes have shrunk slightly and a pool of liquid lard has collected.
Increase heat to medium and continue frying until the fat cubes are a rich golden brown. Do not let them over-darken too much or they will taste scorched and bitter. Scoop crispy lard out of the wok with a slotted spoon and transfer to a plate to cool. Let the liquid lard in the wok cool down slightly, then strain it through a very fine mesh metal sieve.
Once both crispy lard and liquid lard are completely cooled, recombine them in a very clean glass jar. Cover tightly and store in the coldest part of your refrigerator. The liquid lard will turn opaque and creamy as it chills. Only scoop out lard with clean, dry spoons.
This will keep for at least a couple of months. If rancid aromas or flavours develop, throw out the lard and make a fresh batch.