* Grate the onion, carrot, and potato into a medium bowl. Alternatively, process the onion and carrot in a food processor.
* Melt the schmaltz.
* Add the breadcrumbs or matzah meal, the schmaltz, and the spices. Mix to combine.
* Cut the casing in half to make it easier to work with. You’ll end up with two kishkehs, one for now, one you can freeze for later. (You could just as well cook them both.)
* Rinse the casing and tie a knot at one end. Use a sausage funnel, or your fingers, to stuff the casing. (This is a bit messy, but it works.)
* Use your thumb and forefinger to find the opening of the casing. Insert one finger into the opening, then another. Pull your fingers apart slightly, forming an upside down peace sign. Use this space to force stuffing down the casing with your other hand. When you’ve got a lump of stuffing in the casing, carefully push it down towards the knotted end by wrapping your hand around the tube. If air bubbles form, push the stuffing up a bit to let the air out, then back down.
* Continue stuffing the casing and letting out air bubbles. Stop when you have an inch or two of empty casing left. Let out any last air bubbles and knot the casing tightly.
* Repeat with the other casing.
* To cook kishkeh, do any one of the following:
o Poke holes in the casing and fry.
o Poke holes in the casing and fry. Slice into rounds and fry until crisp on both sides.
o Poke holes in the casing. Cook on top of cholent.