Preheat your pellet smoker to 350°F with the lid closed for about 15 minutes. Grease a 10- to 12-inch cast iron skillet or enamel-coated pan and set aside.
In a large bowl, combine strawberries, peaches, sugar, tapioca, vanilla bean paste, orange zest, orange juice, and salt. Stir to combine, then transfer the mixture to the prepared skillet.
To make the biscuit topping, whisk together the flour, sugar, baking powder, and salt in a medium bowl. Using your fingers or a pastry cutter, work in the butter until the mixture resembles coarse crumbs with pea-sized bits of butter. Add the buttermilk and stir just until a shaggy dough forms.
Scoop about ½ cup of dough at a time and drop over the fruit filling. Brush the tops with buttermilk and sprinkle with sugar in the raw.
Place the skillet in the smoker and bake for about 50 minutes, or until the biscuits are golden brown and the filling is bubbling.
Let rest for 15 to 20 minutes before serving with a generous scoop of vanilla ice cream.