As a person who cooks alone I can't finished all the food I make. My girlfriend contributes her best and my friends can also be counted on. But usually there are leftovers of various items that are unavoidable. Repeat offenders in my kitchen: cilantro (sold in the bunch), beans, lime, coconut milk. To combat these leftovers I will sometimes try to buy groceries that can all be used together in various recipes. An easy example presented itself today.
Last night I met with some friends for a fun dinner involving Cosmos (delicious!) and Sex and the City (hot!) and I contributed a dish of Vegan Polenta and Black Bean Enchiladas. What's left? Cilantro (awlays), nutritional yeast nacho "cheese" sauce, lime, black olive slices, and a little red enchilada sauce. Knowing this would happen, I grabbed corn chips and fresh salsa at the store and made a nice helping on Nachos tonight. Just adding in kidney beans and chopped onion.
Now, I understand that nachos are basically enchiladas remixed. But I'm okay with that. The polenta in the enchiladas was what was left after a potato scramble the other day.
With finished product leftovers, I make "grab and go" containers for myself so that I don't make bad food decisions in a hurry (i.e., an entire bag of Veggie Booty for lunch), or I convince people to take them with them to work the next day.