"Extra-lean ground beef and lots of veggies are cooked with diced tomatoes in the Instant Pot® for a hearty chili for a cold day. Top with shredded Cheddar cheese, chopped green onions, and sour cream if you like."
Heat 1 tablespoon oil in a multi-functional pressure cooker (such as Instant Pot(R)) set on the Saute function. Add beef; cook and stir until browned, about 5 minutes. Season with salt and pepper. Drain beef and transfer to a bowl.
Heat 1 teaspoon oil in the pot. Add onion, carrots, celery, red bell pepper, and garlic. Cook until soft, about 5 minutes. Add chili powder, cumin, and red pepper flakes; cook until fragrant, 1 to 2 minutes.
Pour beef broth into the pot; scrape the browned bits of food off the bottom of the pot. Stir in cooked beef, red kidney beans, and white kidney beans. Add diced tomatoes, but do not stir. Close and lock the lid. Select Bean/Chili function; set timer for 10 minutes. Allow 10 to 15 minutes for pressure to build.
Release pressure using the natural-release method according to manufacturer's instructions, 10 to 40 minutes. Stir in lemon juice and tomato paste. Add more tomato paste for a thicker chili. Let sit for 10 minutes before serving.