How to Make It
Sprinkle vegetable rounds evenly with half of the thyme, oregano, sea salt, and pepper.
Spread marinara sauce on bottom of a 6-cup ramekin. Layer slices, overlapping slightly, alternating between tomato, onion, zucchini, squash, and eggplant. Arrange vegetables into a tight spiral. Start with the outer circle, and add a small layer in the middle to fill any gap. Once in place, sprinkle with half of the garlic.
Repeat layering process to create a second layer. Once in place, sprinkle vegetables with remaining thyme, oregano, salt, pepper, and garlic. Drizzle with olive oil and vinegar.
Pour water into bottom of Instant Pot, and put a wire trivet in place. Carefully place ramekin on trivet. Place and lock lid, making sure the steam release handle is set to Sealing. Press MANUAL (High Pressure); set to 6 minutes. Once the time is up, let pressure release naturally for 6 minutes. Carefully remove ramekin. Serve immediately with marinara; sprinkle with basil and Parmesan, if desired.