Set the beef roast out to climatize to room temperature, at least 30 minute
Heat the oil in the pressure cooker, until it starts to smoke. Season the roast. Gently and carefully put the roast in to brown. Do not be in a hurry, let it brown really dark, but do not burn, this will bring out the best flavor.
When the roast is browned nicely on both sides, throw in the onion and garlic.
Put in enough peach juice to cover the roast.
Put on the pressure cooker lid. When pressure begins to escape is the time to start your timer. 45 minutes should make the meat fork-tender.
At the end of 45 minutes, remove the pressure cooker from the stove. Allow it to rest about 15 minutes. Then remove the valve, when all pressure is released, remove the lid.
Place your roast on a platter and allow it to rest, before carving.
While the cooked roast is resting, it is time to make the gravy.
Make a slurry of the corn starch and cold water.
Bring the pot liquid to the boil, stir the slurry once more and pour into the pot liquid, using a (kitchen)whip, lash it gently until it thickens, to an obedient gravy. This being a very simple step.