Ok, so you have a jar of spaghetti sauce.
And after pouring it out into a pan, there's still so much left inside the jar and on the lid.
Add a splash of water.
This much max. You don't want to dilute your sauce.
Put the lid back on.
Give it a good shake. And pour it into the pot as well.
And voila! No waste.
Works with ketchup and BBQ containers as well-- which can be added to any dish with a red sauce or to things like soup.
Here's to little wasting in the kitchen!