Begin by seasoning the chicken thighs with salt and pepper on both sides.
Turn on the Instant Pot and set it to the 'Sauté' mode. Add the olive oil. Once hot, add the diced onions and minced garlic. Sauté for about 2-3 minutes until the onions become translucent.
Add the seasoned chicken thighs to the pot and sear them for about 3-4 minutes on each side until browned. You may need to do this in batches, depending on your pot size.
Once the chicken is browned, add the sliced carrots, cubed potatoes, and green beans to the pot. Sprinkle the dried thyme and rosemary over the vegetables.
Pour in the chicken broth, ensuring it covers the base of the pot. Scrape any browned bits from the bottom of the pot with a wooden spoon to prevent burning.
Close the Instant Pot lid and ensure the steam release valve is set to 'Sealing.' Set the Instant Pot to 'Manual' or 'Pressure Cook' for 10 minutes.
After the cooking time is complete, allow a natural pressure release for 5 minutes, then carefully switch the steam release valve to 'Venting' to release any remaining pressure.
Open the lid, stir the ingredients, and check the seasoning. Adjust salt and pepper if needed.
Serve the chicken and veggies hot, garnished with fresh parsley if desired.