Rinse the liver under cool water, pat very dry with paper towels, and trim away any visible membranes or excess fat.

Place the liver on a cutting board and slice into thin strips about 0.5 centimeter thick so all pieces dry evenly.

Lightly grease dehydrator trays or a wire rack set over a baking sheet if needed to prevent sticking.

Arrange the liver slices in a single layer on the trays or rack, leaving a little space between each piece for air circulation.

Set the dehydrator to 65 to 70 degrees Celsius, or preheat the oven to its lowest setting, usually in the same range.

Place the trays into the dehydrator or oven and dry for 3 to 5 hours in a dehydrator or 2 to 3 hours in the oven, turning the pieces once halfway through.

Check for doneness; the treats should feel firm and dry, not tacky in the center, and should bend slightly without snapping.

Remove the trays and let the liver pieces cool completely on the racks so the last bit of surface moisture can evaporate.

Transfer the cooled treats to an airtight container and store at room temperature for up to 3 days if very dry, in the refrigerator for up to 7 days, or in the freezer for up to 2 months.