How to Make It
In a medium saucepan, cover the yucca with water and boil over moderately high heat until very tender, about 25 minutes for fresh or frozen. Drain well and return to the pan; shake over moderate heat for 10 seconds to dry out the yucca. Pass it through a ricer and add a large pinch of salt. Gently knead the yucca to form a firm dough. Cover with plastic wrap and let cool to room temperature.
Preheat the oven to 350°. In a large skillet, heat the olive oil. Add the onion, red bell pepper and garlic and cook over moderate heat until softened, 7 minutes. Add the turmeric, paprika, cumin and crushed red pepper and cook, stirring, until fragrant, 1 minute. Add the raisins, scallions and vinegar and cook until the vinegar has been absorbed, 1 minute. Transfer the mixture to a bowl; let cool. Spread the Brazil nuts in a pie plate and toast in the oven until lightly browned, 5 minutes; let cool, then chop. Stir the chopped Brazil nuts and mozzarella cheese into the onion mixture; season with salt.
Using lightly oiled hands, pinch off 1 tablespoon of yucca dough and form into a 2 1/2-inch round, about 1/8 inch thick. Add 1 rounded teaspoon of the vegetable-cheese filling and enclose it in the dough, pinching it shut and lightly rolling it into a ball. Repeat with the remaining dough and filling. You should have about 18.
In a medium saucepan, heat 1 inch of vegetable oil to 375°. Working in batches, fry the empanadas, turning, until golden brown and crisp, about 2 minutes per side. Drain on paper towels and serve right away.