McDonald's Korea is struggling once again to secure sufficient amounts of lettuce for its burgers, raising questions about its ability to ensure a stable supply of raw ingredients, according to industry officials, Wednesday. On Tuesday, McDonald's Korea posted a notification on its website saying, “Some restaurants may serve products with little or no lettuce due to unstable lettuce supply caused by weather events. In these cases, a free drink coupon that can be redeemed in our restaurants will be provided with your order.”