Press the 'SAUTE' button, set it to 'MEDIUM' heat, wait until it displays 'HOT'. Add the oil, once it heats up, add the ground beef, leave it undisturbed for 3-4 minutes. Break up the meat into small or large crumbles with a spatula or wooden spoon. Cook the beef until no longer pink and lightly browned.
Next, add the chopped onions, bell peppers, minced garlic and diced jalapeno (if using). Cook, stirring frequently until the onions are translucent, about 2-3 minutes.
Add chili seasoning mix, mix well, and saute for another 1-2 minutes or until the spices are fragrant.
Add tomato paste, and cook for another 1-2 minutes. Make sure there are no browned bits stuck at the bottom of the inner pot at this stage to avoid any potential 'BURN' message. If you do have some, add 1/4 cup of the stock and deglaze the pot by scraping all the browned bits with a wooden spoon.
Add the stock, the diced tomatoes along with the juice, drained and rinsed beans. Mix everything gently.
Press 'CANCEL', close the lid of the Instant Pot with the valve on 'SEALING' position. Press the 'MANUAL' or 'PRESSURE COOK' button and pressure cook on 'HIGH' for 15 minutes. It will take some time for the pressure to build up, after which the timer will start.
Let the pot depressurize for 10 minutes, then do a quick release of leftover pressure as per the manufacturer's instructions. Once the float valve (silver pin) drops, open the lid.
Give the contents in the pot a quick mix. Check for seasoning and adjust with more salt and pepper if required. If you'd like to thicken the chili further, turn on 'SAUTE' and cook until the chili reduces to your desired consistency or see other options listed in the FAQ above. The chili tastes delicious right away but so much better if it is allowed to sit for at least 30 minutes to overnight before serving, as the flavors have a chance to mingle and intensify.