In a large mixing bowl, combine the Greek yogurt, honey or maple syrup, vanilla extract, and sea salt. Whisk vigorously until the mixture is completely smooth and well combined. Taste and adjust sweetness if needed.

If using fruit puree, gently fold it into the yogurt mixture. For swirl effects, you can add the puree in ribbons rather than mixing completely. For other mix-ins like chocolate chips or nuts, reserve them for the final step.

Cover the bowl with plastic wrap and refrigerate for at least 1 hour. This helps the flavors meld together and ensures a smoother freezing process.

Transfer the chilled mixture to a shallow freezer-safe container. If you have an ice cream maker, churn according to manufacturer's instructions. Without one, freeze for 2 hours, then remove and stir vigorously to break up ice crystals. Repeat every 30 minutes for 2-3 more times until desired consistency is reached.

Once the frozen yogurt reaches a soft-serve consistency, fold in any additional mix-ins like chocolate chips or cookie pieces. Transfer to an airtight container and freeze for another 2-3 hours until firm.

Let the frozen yogurt sit at room temperature for 5-10 minutes before scooping. Serve with fresh fruit, a drizzle of honey, or your favorite toppings for the perfect homemade treat.