Mix lamb and beef with egg, crumbs, oregano, garlic, onion, pepper, and parsley.
Shape into 6 burgers.
Chill until ready to grill-Preheat stovetop grill.
Grill burgers over high heat until golden brown on the outside and medium done on the inside, or to taste.
Turn burgers as necessary.
Remove lamb burgers to serving dish.
Sprinkle with crumbled feta cheese and olives.