Turn the Instant Pot to saute and let heat until it reads HOT, or for 2-3 minutes.
Add in 1 teaspoon of the oil. Pierce each sausage several times with a fork and then place the sausage into the oil and sear on each side until browned, about 2 minutes per side. Once browned, remove the sausage from the inner pot and place them onto a clean plate.
With the pressure cooker still on the saute setting, add in an additional teaspoon of oil, along with the sliced peppers and onions. Saute for 3-4 minutes or until the vegetables have begun to soften. Turn the Instant Pot off.
Add in the stock, and use a wooden spoon to scrape up any browned bits on the bottom of the inner pot.
Add the sausage back to the inner pot. Add in the garlic and then spoon the tomato sauce over the sausage.
Set to cook on high pressure for 6 minutes. Once the cooking time has elapsed, allow the pressure to release naturally on its own for at least 10 minutes.
Serve on buns, over pasta or rice, or as a stand-alone meal.
