Step 1

In a medium bowl, stir together the water, tomatoes and their juices, olive oil, balsamic vinegar, garlic powder, oregano, kosher salt, spinach, and whole basil leaves.

Step 2

Ladle just enough of the tomato mixture into the Instant Pot to cover the bottom.

Step 3

Break the spaghetti noodles in half. Working in batches, add the noodles to the Instant Pot in a fan shape so that they stack on each other, making as much space between the noodles as possible (if the noodles are directly next to each other they clump up — it doesn’t have to be perfect, just try to fan them out to make space).

Step 4

Pour remaining sauce over the spaghetti.

Step 5

Press the Pressure Cook button, making sure the “High Pressure” setting is selected, and set the time. Note that it takes about 10 minutes for the pot to “preheat” and come up to pressure before it starts cooking. (During cooking, avoid touching the metal part of the lid.)

Step 6

Quick release: Vent the remaining steam from the Instant Pot by moving the pressure release handle to “Venting”, covering your hand with a towel or hot pad. Never put your hands or face near the vent when releasing steam. Open the pressure cooker lid.

Step 7

Open the lid and stir, removing any clumps. Then remove the pot from the Instant Pot and allow to cool for 3 to 5 minutes for the sauce to thicken slightly. The sauce will thicken even more as it cools. Ladle into bowls and serve.