Place the steak strips, flour, salt, and pepper in a slow cooker.
Stir the mixture until the steak is well coated with the flour.
Add the onion, tomatoes, mushrooms, green pepper, and soy sauce.
Stir to combine.
Cover the slow cooker and cook for 4 hours on high or 7–8 hours on low.
Serve with rice or buttered noodles.
Notes
You can substitute diced tomatoes for the crushed tomatoes, if you'd like.Add a veggie and a hunk of bread, and dinner is done! Make it ahead: let cool and store in the refrigerator for 1–2 days, or until you're ready to enjoy it. Reheat it in the microwave, in the crockpot, or in a skillet on the stovetop.Freezing instructions: freeze any leftover steak and sauce in a resealable freezer bag. Freeze for up to 2 months. Defrost in the refrigerator for 24 hours, then re-warm.