Combine the pork mince, egg, crumbs, pistachios, chilli, spices, onion, coriander leaves and lemon zest in a bowl. Mix well, and form into 5 cm burgers. Refrigerate for 30 minutes.
Preheat a frying pan over medium heat. Cook burgers for 5 minutes on each side, or until light golden and cooked through. Drain well on kitchen paper.
Combine the radish, fennel and salad leaves.
Grill the burgers buns until golden, and top each with some fennel salad and a warm pork burger. Drizzle with yoghurt, and serve with a sprinkling of smoked paprika and fennel fronds.
BBQ or Grill