Press the Sauté button on your Instant Pot and let the pot heat up for about two minutes. Combine the beef, onion, carrots, celery, and garlic and sauté for about 3 minutes, stirring occasionally.
Add the broth and cancel the Sauté function.
Add the chopped tomatoes, green beans, thyme, and bay leaf to the pot. Stir to combine.
Lock on the lid, select the Pressure Cook function, and adjust to high pressure for 10 minutes. Make sure the steam valve is set in the “Sealing” position.
When the cooking time is up, let the pressure release naturally for 5 minutes, then quick-release the remaining pressure.
Remove the lid and stir in the lemon juice, salt, pepper, and balsamic vinegar. Use tongs to remove and discard the bay leaf.
Serve immediately, or cover and refrigerate for up to 4 days.
If you prefer to use all frozen vegetables in this recipe, use 1 16-ounce package of mixed frozen vegetables. You don’t need to sauté the frozen vegetables so you can skip steps 1 and 2 and just add everything to the pot at the same time.
STOVETOP DIRECTIONS: Follow the directions as is, but use a large lidded pot. When you get to step 4, place the lid on your pot and let the soup simmer for 20 minutes or until the meat is cooked through.