By far my favorite way I've found to reduce waste in our kitchen is once a month cooking. Now, I don't only cook 1x a month, but I do a large amount of prep work once a month, and freeze it for use later in the month. For example, I will cook 3 lbs of hamburger meat, and divide it up into 3 freezer bags, and then have it throughout the month- simply remove and dethaw! Wha-lah! Ready to sprinkle taco seasoning onto, or mix with Spaghetti sauce or whatever else you want to use it for! I love doing this, because I mess up the kitchen, use every pot and pan in the house, for one Saturday or Sunday per month, and when I'm done, I have most of the meat for the month done!
Lots of time I will also prep out entire meals- simply prep them to the cooking point, and freeze! Or you can cook them, and then cool/freeze- but I prefer prepping to the cooking point, and then freezing. Cooking then cooling just takes too much time, I find, but that's just me! I love it- when my son gets off the bus, I pop dinner in the oven, and my house smells wonderful when my husband comes home from work! No mess, no fuss, and the only thing we have to decide is what vegetable we're having!
I know you're also thinking, yuck, I hate casseroles! I agree to a certain point- and when I refer to casseroles, I don't mean chicken, rice, and vegetable mixed together with a can of soup poured over and frozen. You can freeze stuffed peppers- prep them, put in a dish, and pour tomatoes over them, and freeze. You can also freeze stuffed cabbage or baked macaroni and cheese. And, now with all the sales on baking supplies, you can make cookie dough and freeze it, but more on that in another post!