1.Combine mince, cumin, garlic, coriander, salt and pepper in a medium bowl. Using your hands, shape mixture into four patties to fit the size of the bread slices.
2.Grill bread on heated, oiled grill plate until browned on both sides. Transfer to a plate.
3.Cook the patties, eggplant, tomatoes and onion on a heated, oiled grill plate (or barbecue) until the patties and vegetables are browned and just cooked though.
4.Meanwhile, combine hummus, juice and oil in a small bowl.
5.Layer four toasted bread slices with rocket, eggplant, patties, tomatoes, hummus and onion. Top with remaining bread slices before serving.