Advance preparation: 2 hours or as long as overnight for marinating the pork.
1. Place the cubes of pork in a large mixing bowl. Sprinkle the salt, coriander, and pepper over them and stir well to coat.
2. Grate the onion over the pork using the large holes of a box grater. You can also finely chop the onion in a food processor and spoon it over the pork. Stir to mix. Tightly cover the bowl with a couple of layers of plastic wrap to keep the onion scent from permeating your refrigerator. Let the pork marinate in the refrigerator for at least 2 hours or as long as overnight, stirring it a couple of times so it marinates evenly. The longer the pork marinates, the richer the flavor will be. (As far as most Russians are concerned, you can never have enough onion.)
3. Drain the pork well, discarding the marinade, and thread the pork onto the skewers.
4. Set up the grill for direct grilling and preheat it to high.
5. When ready to cook, brush and oil the grill grate. Arrange the kebabs on the hot grate and grill the pork until it is sizzling, nicely browned on all sides, and cooked through, 2 to 3 minutes per side, 8 to 12 minutes in all.
6. Using tongs, slide the pieces of pork off the skewers onto plates or a platter. Serve the pork with Russian black bread (grilled if you like).