16 ounces top sirloin, cleaned and trimmed

2 teaspoons sherry vinegar

1/2 teaspoon dry mustard

2 large egg yolks

1/4 cup light olive oil

6 tablespoons finely diced shallots

2 tablespoons small, brined capers, drained and unrinsed

1 teaspoon kosher salt

1/4 cup celery leaves, finely chopped and divided

2 tablespoons fresh parsley, finely chopped and divided

1 teaspoon freshly grated lemon zest