Each recipe in a day has a button under its name that says Make Fresh or Leftovers. Tap it and choose the other one to switch.

Choose Leftovers when you’re eating something you already cooked. Its ingredients aren’t added to your shopping needs again, it doesn’t count as cooking time for reminders, and there’s nothing to mark as made.

On a meal more than one person is eating, switching changes it for everyone: it’s the same pot.