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.
Add olive oil to cooker, and heat until fragrant, about 1 minute. Add onion, carrots, and celery; cook, stirring often, until vegetables are softened, 2 to 3 minutes. Stir in garlic and crushed red pepper, and cook 30 seconds. Stir in chicken stock, thyme, collards, tomatoes, ham hock, and black-eyed peas. 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 10 minutes. (It will take 10 to 15 minutes for cooker to come up to pressure before cooking begins.) Let the pressure release naturally for 15 minutes.
Carefully turn steam release handle to VENTING position, and let steam fully escape (float valve will drop). (This will take about 2 to 3 minutes.) Remove lid from cooker.
Remove ham hock from cooker; pull meat off bone, and chop to equal about 1/3 cup. Discard bone. Stir chopped ham, vinegar, salt, and pepper into soup.
If you make this soup with fresh, in-season, peas no need to soak.