Mince the garlic and chop the onion. Place those into the PC. Add in 1/2 cup of water and sautee. Use a wooden spoon or spatula to stir the onions and garlic while it sautees for 5 minutes.
Remove the inner pot from the PC ad add in the rest of your ingredients except for the basil. Put the pot back in the PC and put the lid on. Set the PC to manual for 15 minutes on high pressure and make sure the steam release handle is set to 'sealing'.
Once the time is up, move the steam release handle to 'venting.' Remove the lid and place the chopped basil in the pot. The take an immersion blender and blend the sauce right in the PC until it is smooth.
Sautee and let it boil for 10 minutes or until it reaches the desired consistency. Hit the 'warm/cancel/ button and let the sauce cool down a bit and place air tight mason jars. Store in the fridge for up to 2 weeks. Before using, just check and make sure the sauce is still fresh.
Notes
It is very difficult to find a marinara sauce that doesn't have any oil in it. This recipe has you covered.