Set the Instant Pot to the "Sauté" function. Once it’s hot, add a little oil and the ground beef. Brown the meat for 5-7 minutes, breaking it into small pieces. Add diced onion and garlic, and sauté for another 2-3 minutes until the onions soften.  Drain any excess fat if necessary.

Season the Beef: Add the taco seasoning to the beef mixture and stir well to coat. At this point, you can also add salt and pepper.

Pour diced tomatoes, green chilies, and beef broth (or water) into the can. Stir to combine everything. Add the egg noodles, making sure they're submerged in the liquid.

Pressure Cook: Close the Instant Pot lid and set the valve to the "Sealing" position. Cook on Manual High Pressure for 3 mins. Once the timer is up, perform a quick release by carefully moving the valve to "Venting."

Once the pressure is fully released, open the lid and stir everything. Stir in the shredded cheddar cheese and sour cream until the mixture becomes creamy and cheesy. If the dish seems too thick, add more beef broth or water to adjust the consistency.