Turn on the saute setting. Pour the oil into the inner pot. When hot, add the onions, celery, and carrots, cooking for 4-5 minutes until veggie sbegin to soften.
Add the garlic, tomato paste, salt, pepper, and paprika to the veggies, cooking for 30 seconds more. Stir well to scrape any bits from the bottom of the pot. Turn off the saute setting.
Add the potatoes, zucchini, green beans, diced tomatoes, bay leaves, lentils, and broth to the pot. Stir to combine.
Seal the lid and cook on Manual setting (high pressure) for 6 minutes.
When cook cycle is complete, allow the pot to depressurize naturally for 10 minutes. Then open the valve and release remaining pressure.
Stir the stew. Optional thickening step: ladle out 2 cups of vegetables into a deep container and puree until smooth with an immersion blender. Add the pureed mixture back to the hot stew and stir to combine.
Serve immediately. Top with parmesan cheese or chopped parsley if desired.