In a small bowl, bloom the gelatin in 1/4 cup of orange juice. Let it sit while bringing the remaining 3/4 cup of orange juice to a simmer for 10-15 minutes until reduced to a syrup or in half. (If using frozen concentrate only, bloom the gelatin in water for 3 minutes).
Remove the simmering orange juice from the heat, then whisk in the bloomed gelatin until fully dissolved. (If using frozen concentrate only, whisk the concentrate into the gelatin).
Add the orange zest, salt and optional honey to the orange juice mixture. Let it cool to room temperature for about 10 minutes.
Once cooled, whisk in the plain yogurt and vanilla extract until well combined.
Pour the mixture into popsicle molds or panna cotta molds, leaving a bit of space at the top for expansion.
Freeze (for popsicles) or refrigerate (for panna cotta) for at least 4-6 hours or until fully set.