In a saucepan, combine the sugar, tapioca starch, sea salt, and water. Whisk the mixture until it is smooth and well blended.
Place the saucepan over medium heat and continuously stir until the mixture thickens and begins to bubble, which should take about 5-7 minutes.
Once thickened, remove the saucepan from the heat and mix in the lime juice. Let the mixture cool for a few minutes.
Carefully fold the sliced strawberries into the cooled mixture, ensuring they are evenly coated.
Transfer the strawberry filling into the pre-baked pie shell, smoothing it out with a spatula.
Chill the pie in the refrigerator for a minimum of 2 hours to allow it to firm up.
When ready to serve, slice the pie and garnish with fresh mint leaves if desired.