How to Make It
Select SAUTÉ setting on a programmable pressure multicooker (such as Instant Pot). (Times, instructions, and settings may vary according to cooker brand or model.) Select HIGH temperature setting, and allow to preheat 2 to 3 minutes. Melt butter in cooker; add carrots, onion, celery, and 1 teaspoon of the salt. Cook, stirring occasionally, until vegetables start to soften, about 5 minutes. Add garlic, and cook, stirring occasionally, until fragrant, about 1 minute. Add diced tomatoes, vegetable broth, potatoes, lima beans, and Parmesan rind. Press CANCEL.
Cover cooker with lid, and lock in place. Turn steam release handle to SEALING position. Select MANUAL/PRESSURE COOK setting. Select HIGH pressure for 3 minutes. (It will take 12 to 15 minutes for cooker to come up to pressure before cooking begins.)
Carefully turn steam release handle to VENTING position, and let steam fully escape (float valve will drop). (This will take 2 to 3 minutes.) Remove lid from cooker. Remove and discard Parmesan rind. Stir in thyme leaves and remaining 1/2 teaspoon salt. Serve immediately sprinkled with parsley and pepper.