Ingredients
Method
1.Combine lamb, onion, egg yolk, breadcrumbs and half the sumac in medium bowl; shape mixture into four patties.
2.Cook patties on heated oiled grill plate (or grill or barbecue) until cooked.
3.Meanwhile, preheat grill. Trim ends from bread; cut remaining bread into quarters then halve pieces horizontally. Toast, cut-sides up, under grill.
4.Combine remaining sumac and tzatziki in small bowl. Combine watercress and juice in another bowl.
5.Sandwich tzatziki mixture, beetroot, patties and watercress between bread pieces.
Tzatziki is a Greek yoghurt dip made with cucumber, garlic and sometimes chopped fresh mint. You can buy tzatziki ready-made in supermarkets and delis.
Note