Season both sides of the brisket with salt. Set the Instant Pot to saute and add the oil. Put in the brisket and cook until deeply brown on both sides.
While the meat browns, cut the pear off the core in four cuts. On a box grater, grate the flesh of the pear and discard (or eat!) the skin.
Add the sesame oil, mirin, rice vinegar, soy sauce, brown sugar, pepper, pear, and garlic to the pot and stir. Nestle the meat into the sauce, fatty-side up. Put the lid on the Instant Pot, set it to “Meat” for 1 hour and 25 minutes, being sure to close the steam nozzle.
When the meat is done. Turn the nozzle to release the steam, remove the lid, and transfer the meat to a cutting board. Skim any obvious fat at the top of the liquid by laying a large spoon on the surface and allowing the fat to drift into the spoon.
Trim off the obvious fat from the meat and discard. (It may not look like a lot of meat remains, but it's very flavorful, so a little goes a long way). Shred the meat or use a knife to cut into thin slices and put into a serving bowl. Pour about the juices from the pot over the meat. Scatter with scallions. Stir and serve with warm tortillas, kimchi, and slaw.