Yes! You can freezer pepper steak before or after cooking. To freeze it before, slice the meat, peppers and onions and place into a freezer safe bag. Pour the sauce into a separate bag. Store in the freezer for up to 6 months. When you're ready to use, cut open both bags and place the ingredients into the slow cooker while frozen. Cook on low for 6 hours. Slow cooker pepper steak can be frozen after cooking by placing the entire meal (even rice!) into freezer safe bags and freezing for up to 3 months (for optimal quality). Defrost overnight in the fridge.