Whisk together yogurt, milk, honey, lemon juice, zest, vanilla, and salt in a bowl until smooth.
Pour the mixture into a Ninja Creami pint container, ensuring you stay below the max fill line.
Place the lid on the pint and freeze on a level surface for exactly 24 hours.
Remove the pint from the freezer and place it in the Ninja Creami outer bowl assembly.
Select the "Lite Ice Cream" or "Frozen Yogurt" program and allow the machine to process.
If the texture appears crumbly, add 1 tablespoon of milk and select the "Re-spin" program.
For mix-ins like graham crackers or fruit, use a spoon to create a hole in the center, add ingredients, and use the "Mix-in" program.
Serve immediately for the best soft-serve consistency.