Step 1

Select Saute to preheat the pressure cooking pot. Add the oil. When hot, add the pepper and onion and cook for 3-4 minutes, until softened.

Step 2

Meanwhile, in a 7-inch round cake pan, stir together the tomatoes, garlic powder, basil, red pepper flakes, and salt.

Step 3

When the vegetables are softened, add the meatballs and stock or water to the pressure cooking pot. Use a wooden spoon to scrape up any browned bits on the bottom of the pan and stir everything together.

Step 4

Place a trivet in the pressure cooking pot and use a sling to carefully lower the pan with the tomato sauce onto the trivet. Lock the lid in place. Select High Pressure and 3 minutes cook time.

Step 5

When the cook time ends, turn off the pressure cooker. Use a quick pressure release. When the valve drops, carefully remove the lid. Use the sling to remove the pot of sauce from the pressure cooking pot. Remove the trivet and add the sauce to the meatballs. Stir to combine. Switch to the Keep Warm setting until ready to serve.

Step 6

If you like, toast the sub rolls in a toaster or under the broiler. Pile the meatballs and sauce onto the sub rolls and top with mozzarella. Place the sandwiches on a baking sheet under the broiler to melt the cheese. Keep a close eye on the sandwiches under the broiler to prevent burning.