I always want to put some small amount of fresh fruit on the table for breakfast. For the longest time, I would forget it until I was landing the main breakfast plate on the table -- eggs, oatmeal...oh yeah! the fruit! I finally gave myself a motto to remember: "fruit first!"
After coffee was made and consumed of course! The motto for coffee is: Drink your coffee first before helping other passengers with their beverage.
As to remembering and planning meals, I occasionally get short bursts of inspiration regarding food and what is in the fridge and pantry. At these times, I will write down a list called "Eat This!" which will include all the combinations that are inspiring me at the moment. Then when I need to create something for us to eat and my brain is tired, I peruse the list. Oh yeah! We have that fresh spinach and a small piece of feta cheese! (spinach and feta omlette for breakfast). Or I found the golden raisins in the back of the pantry! (oatmeal raisin cookies or just a bowl of oatmeal). It is a welcome nudge that keeps us from having to do take-out.
I do realize this is not exactly what you were asking about. But you know, that missed ingredient can hide in different ways.