Put the lamb mince, lemon zest, ground cumin, chillies, garlic, cheese and mint in a large bowl, and mix together with your hands until all the ingredients are thoroughly combined.
Shape the mixture into 4 burgers, brush all over with 1 tablespoon of the oil, and cook in a large nonstick frying pan or griddle pan for 5-6 minutes on each side. Set aside on a plate to rest.
Prepare the pickled cucumber. In a pan over a medium heat, cook the cucumber for 1 minute. Add the ground coriander and mustard seeds, sugar and vinegar along with 15ml boiling water and cook for a further 2-3 minutes until softened. Remove from the heat and allow to cool slightly before serving with the burgers.
Brush the ciabatta halves with the remaining oil and griddle, cut-side down, for 1 minute until golden. Top with a burger and serve with the pickled cucumber and a little of the sauce.