do something from scratch
Entirely without the aid of something that is already prepared or in existence. Refers to making something, usually food, from the raw or base ingredients or components, rather than those that have been preassembled or already partially completed. She doesn't have time to make cupcakes from scratch, so I'm sure they're from a box. My template got deleted so now I have to craft the whole report from scratch. If you want some real from scratch cooking, try Jesse's Café—it's as close to homemade as it gets.
See also: scratch