Press Saute and wait until Instant Pot says Hot. Add olive oil, bell pepper, onion and garlic. Saute for 5 minutes, stirring occasionally. Then add paprika and Italian seasoning and cook for 1 more minute, stirring once. Press Cancel.
Add cabbage, celery, carrots, diced tomatoes, broth, salt and pepper. No need to stir but you can. Close the lid, set valve to Sealing and press Pressure Cook on High or Manual for 5 minutes.
After wait 10 minutes and then turn pressure release valve to Venting to release remaining pressure.
Add butter and lemon juice, stir the soup and let soup sit for 10-15 minutes uncovered or half way covered to allow the flavors to "marry each other". Taste and adjust any seasonings to taste. Serve hot with a slice of bread.
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Notes
Store: Refrigerate soup leftovers in an airtight container for up to 5 days.Freeze: This soup will freeze well as it contains sturdy veggies. Freeze in an airtight container, leaving some room for expansion, for up to 3 months. Thaw in the fridge overnight or on the counter for 5-6 hours.