Place the coriander seeds into a mortar and pestle and grind until semi-fine. Mix together with the freshly ground black pepper and salt and set aside.
Slice the sirloin into strips approximately 15cm long (the length of the steak), 2cm wide and 1cm thick.
Drizzle olive oil onto the beef strips, generously rub with the coriander spice mixture and weave the beef strips onto the skewers.
Add a splash of olive oil to a hot griddle pan and grill the skewers in batches, turning to cook on all sides to your preferred doneness; it will take approximately 5 minutes for medium-rare which is recommended.
To make the dipping sauce, combine the yogurt with the lemon juice, zest and dill and season to taste with salt. Serve!