Combine the breadcrumbs and taco spice mix on a plate. Whisk the egg and milk together in a bowl. Toss the chicken in the flour then dip in the egg mixture. Roll in breadcrumb mixture to coat.
Combine the mayonnaise, lime juice and half the sour cream in a large bowl; season to taste. Add the slaw and mix to combine.
Preheat oven to 200 degrees C. Line a baking tray with baking paper. Arrange the taco shells on tray; bake according to packet instructions.
Meanwhile, heat the oil in a wok or deep saucepan over medium-high heat. Deep-fry chicken for 3 to 4 minutes or until cooked through. Drain on absorbent paper.
Place the tacos on a serving platter. Spoon coleslaw into tacos. Top with cheese and crispy chicken. Dollop some salsa and remaining sour cream on top; sprinkle with coriander leaves and serve with lime wedges.