Soak raisins and currants in a bowl of warm water for 30 minutes. Drain and pat dry with paper towels.
Mix 2 tablespoons milk with yeast in a large bowl until dissolved. Add remaining milk, flour, egg, and salt; beat with an electric mixer until dough is smooth. Stir in raisins and currants. Cover dough with a clean dish towel. Let rise in a warm place until doubled, about 1 hour.
Heat oil in a deep-fryer or large saucepan to 375 degrees F (190 degrees C). Drop portions of dough into the hot oil using 2 lightly greased tablespoons or an ice cream scoop. Cook until golden brown, about 3 minutes per side. Drain on a paper towel-lined plate. Repeat with remaining dough.
