Add eggs, yogurt, vanilla, lemon zest, and salt. Mix well.
Stir in flour 1/2 cup at a time until dough forms into a manageable ball.
Turn out onto a lightly floured surface and knead for 5 to 10 minutes, adding flour as necessary, until dough is soft and pliable, but not sticky. (You may need up to 5 cups flour.)
Place dough in a large, lightly greased bowl.
Cover and let rise in a warm place until doubled, about 1 hour.
In a small bowl, toss dried fruit with confectioners' sugar.
Punch down dough, transfer to floured surface, and knead in the fruit.
Line cupcake tin with liners and divide dough evenly between them.
Cover loosely with dish towel, and let rise 30 minutes.
Brush with melted butter, if desired.
Bake for at 350 F for 25 minutes, or until cupcakes are golden brown and a toothpick inserted in the center comes out clean.