Set up your bag holders, attach your bags, and add two chicken breasts to the bags.
Pour the frozen chopped onions into the bags over the chicken.
Pour the bell peppers into the bag.
Pour the peas and carrots into the bag.
Add the diced tomatoes.
Add the tomato sauce.
Add the Italian seasoning.
Add the garlic granules (or powder).
Zip the bag closed and moosh the bag around a bit to distribute the tomato sauce around the other ingredients.
Lay flat and freeze until ready to cook. Remember that if you want to cook this in an Instant Pot, you'll need to either thaw it a bit, or freeze it in round containers instead of a bad so that the frozen food fits into the Instant Pot insert.
Slow Cooker Instructions
Thaw the bag in the fridge overnight, then pour all the contents of the bag into a slow cooker. You slow cooker should be sized so that the food fills at least half of the crock, otherwise your chicken could end up dry.
If using, add the Italian dressing and/or balsamic vinegar.
Add the remaining ingredients to the slow cooker and set temperature to low. Cook for 6-8 hours.
Instant Pot Instructions
Pour the contents of the bag into your IP insert.Add the remaining ingredients, and stir a bit.Secure the IP lid and close the vent valve.Press the "Manual" button and adjust cook time to 30 minutes. Note that because you are cooking from frozen, it can take much longer for your IP to come to pressure. Sometimes up to 20 minutes.When cooking is done, allow for a 10 minute natural release. Open the valve to release any remaining steam. You can now serve as is, or shred your chicken to serve over pasta.
Please note that the nutrition data given here is a ballpark figure. Exact data is not possible.