3 Tbsp olive oil, divided
1 medium eggplant
1 medium onion, diced
2 cloves garlic, minced
1 28-oz can plum tomatoes
3 Tbsp balsamic vinegar
1/4 cup chopped fresh basil leaves
3/4 tsp dried oregano (or 2 tsp fresh)
1/2 tsp red pepper flakes (optional)
1/2 tsp salt
1/4 tsp pepper
1/2 to 1 cup freshly grated Parmesan cheese
3 Tbsp Panko or other breadcrumbs
Cut the eggplant lengthwise into 1/2 “ slices. Press Saute on the Instant Pot and when the display says Hot, add two tablespoons oil. Saute the eggplant until lightly browned on both sides. Transfer them to a plate and add another tablespoon of oil and the onions to the pot. Saute for a few minutes until tender, then stir in the garlic.
Drain and coarsely chop the tomatoes. Add them to the pot with the balsamic vinegar, basil, oregano, red pepper flakes, if using, and salt and pepper. Saute and stir for a few minutes to reduce any excess tomato juice and then hit Cancel.
Spray a 7-inch pan with cooking spray and sprinkle with one tablespoon of breadcrumbs. Lay half the eggplant slices over the crumbs. Sprinkle another tablespoon of breadcrumbs over the eggplant, then half the tomato/onion sauce followed by half the grated Parmesan. Repeat these layers, ending with the cheese. Cover the pan with tin foil. Wash and dry the Instant Pot.
Put 1 1/2 cups of water and the trivet in the Instant Pot. Wrap the bottom of the pan with tin foil if you want. (Not necessary, but it might prevent leakage.) Put the pan on the trivet and close the pot. Make sure the valve is set to Sealing. Push Pressure Cook (or Manual) and adjust time using the + and - buttons to get to 15 minutes. When it beeps that it's done, leave it for a 5-minute natural release and then flip the valve to Venting for a quick release and when the pin drops remove the lid.
If you like, pop this under the broiler for a few minutes to brown the top but whether you do this or not, let it sit on the counter for 10 minutes or so before removing the outer ring. It needs time to set or it may fall apart. Then run a knife around the edge and remove the outer ring. Use a spatula to loosen the bottom and slide the lovely Eggplant Parmesan onto a plate.