The Select meals window lists inactive recipes too (they sort after active ones), so you can add one. On the menu table it then shows a Disabled ribbon and greyed styling. Be aware that:

• Clone skips inactive meals - they are not copied to other dates.
• Randomly Generate a Menu only picks active meals.
• In the current version the menu list on the customer site is filtered elsewhere by the recipe's active status, so a disabled meal on the menu is generally not orderable - re-enable the recipe if you want it sold.

Use the pencil icon in the ACTIONS column to open the recipe and reactivate it.