Prepare the filling by heating 2 tablespoons of olive oil in a large skillet over medium-high heat. Add the diced onions and minced garlic, sautéing until softened and fragrant, about 3-4 minutes.

Add the ground beef to the skillet, breaking it apart with a wooden spoon. Cook until browned, about 6-8 minutes. Drain excess fat if necessary.

Stir in the diced tomatoes, bell peppers, cumin, paprika, salt, and black pepper. Cook for 5 minutes until vegetables are tender and flavors are combined. Remove from heat and let cool completely.

In a large mixing bowl, combine the tapioca flour and salt. Gradually add warm water while mixing with your hands until a soft, pliable dough forms. The dough should be smooth and not sticky.

Divide the dough into 16 equal portions. Roll each portion into a ball, then flatten into a 4-inch circle using your hands or a rolling pin on a lightly floured surface.

Place 2 tablespoons of the cooled beef filling in the center of each circle. Fold the dough over to create a half-moon shape and press the edges firmly to seal. Use a fork to crimp the edges for a decorative finish and to ensure a tight seal.

Heat vegetable oil in a deep skillet or Dutch oven to 350°F. Carefully add 3-4 turnovers at a time, frying for 3-4 minutes per side until golden brown and crispy.

Remove the salgadinhos with a slotted spoon and drain on paper towels. Serve hot with lime wedges and hot sauce if desired.