The Supporting Actress Saves Herself Thanks to the On-Screen Comments

Looking for a Book. If You Know One, Please Recommend It. I'm Begging You

I'm trying to find a book, but I've forgotten the names of the male and female leads. I only remember a few details: the male lead has to put scallions in someone's food, then pick them back out for them. Also, the male lead and the female lead's brother invent something and get into trouble, so the female lead goes to ask the male lead for help.