Press the saute button on the Instant Pot. Add the olive oil.
Add the chopped onions to the pot. Sprinkle with the salt. Allow to cook for about 5 minutes or until almost translucent, stirring frequently.
Add the garlic, stir and allow to cook for one minute.
Add the Italian sausage to the onion/garlic mixture. Stir frequently until cooked half way.
Add the dried basil, dried oregano, red pepper flakes, and crushed tomatoes.
Turn off the saute function. Set the manual mode for 20 minutes, and allow the pressure to release naturally. My Instant Pot took about 20 minutes to rise to pressure and about 10 to release the pressure.