Lemonade
Fresh lemon juice, water and a sugar syrup cooked for two minutes so it actually dissolves. Three ingredients, half an hour including the time it takes the syrup to cool, and it makes half a gallon.
At a glance
Ingredients and method are in the app
Kitchen Pantri holds the full ingredient list and step-by-step method for Lemonade, checks it against what is already in your pantry, and adds anything missing to your shopping list. The app is free to use; you set up a Pantri account when you first open it.