Place all ingredients except tortellini in one large resealable freezer bag.
Add the tortellini to a second bag.
Remove excess air and seal both bags. Staple together above the seal, and freeze.
Thaw overnight in the fridge.
Dump the bag contents with the diced tomatoes into slow cooker and cook on low for 2-3 hours.
At 20-30 minutes before serving, add the tortellini and allow to cook. Adding it too soon will let it overcook, making it mushy.