Pat brisket dry with paper towels and sprinkle with a generous amount of salt on each side. Let brisket sit at room temperature for 30 minutes.
Heat oil using the saute function of a 6 or 8 quart Instant Pot. Once hot, brown brisket on both sides, about 3-4 minutes per side. Remove the brisket and shut off saute function.
Place onions and garlic inside of the liner and then place the brisket on top.
Whisk together broth, ketchup, sugar, salt and pepper. Pour over the brisket.
Cook on high pressure for 60 minutes, with a natural release.Once done, shred the brisket, or slice across the grain. Serve in tacos, or as a main dish for a celebration.