Trim excess fat from the brisket and cut in half, across the grain. Salt and pepper both sides, reserving 1 tsp of the salt.

Turn on the pressure cooker's sauté setting. When hot, add the oil, then the brisket halves. Brown a few minutes on each side to get a bit of a crust. Remove to a plate.

Pour the apple cider/juice into the pot and scrape the brown bits from the bottom of the pot (deglaze). Turn off the sauté function.

Add the onion, garlic powder, liquid smoke, and stir.

Place the brisket halves in the liquid and pour the chili sauce over the meat. Do not stir.

Place the lid on the pot and lock in place. Set the steam release knob to Sealing.

Press the Pressure Cook/Manual button (or dial), and then the + /- button (or dial) to choose 90 minutes (High pressure).

When the cooking cycle ends, let the pot sit undisturbed for 15 minutes (15 minute Natural Release). Then turn the steam release knob to Venting and release any remaining steam/pressure.

When the pin in the lid drops down, Open the lid facing away from you.

Test the tenderness of the brisket using tongs or a long handled utensil. If the meat isn't as tender as you'd like, immediately put the lid back on and cook for another 10 minute cycle with a 10 minute natural release.

Use tongs to remove the brisket to a plate and cover with foil.

Turn the sauté function back on.

Stir in the brown sugar. Taste and add as much of the reserved tsp of salt as desired.

Mix the cornstarch with 2-3 Tbsps of cold water and stir, to make a slurry. Whisk into the simmering sauce. If it doesn't get thick enough after a couple of minutes, make some more slurry and add a little at a time until sauce has desired thickness. 

Turn off the pot and use oven mitts to remove inner pot to a cooking rack.

Slice the brisket across the grain and add the slices into the sauce. Let them stay in the sauce for a few minutes while you get the rest of your meal prepared.

Serve with mashed potatoes or rice, or on buns.