Preheat skillet over medium-high heat. Cook beef with a small amount of olive oil until browned and cooked through.
Transfer beef to a bowl and let cool slightly.
Assemble individual bowls with cucumber, cherry tomatoes, olives, and feta.
Toss olive oil, lemon juice, oregano, salt, and pepper to make dressing.
Drizzle dressing over bowls and top with cooked beef.