Form lamb into 2, ¼-inch patties + season with salt/pep + seasoning blend; heat 1 tsp oil in skillet over med-high + cook patties 2 min until browned; flip over + cook 2-4 min until cooked through + no pinkness remains

Meanwhile, cut onion in half from root to stem, peel + thinly slice ½ (or whole) of onion; set aside

On 2 plates, use 4 large lettuce leaves to form the top + bottom halves of each burger, then nestle burger between lettuce 'buns'

Dollop each with 1-2 tbsp tzatziki + top with sliced onions