Stir; strain; up; garnish.
Frederic Yarm (at link) suggests an orange, lemon, or grapefruit twist as an alternative garnish, and Angostura or orange bitters as alternative bitters if needed.
I used a grapefruit twist. This was lovely.
Reposado Tequila, Bianco Vermouth, Celery bitters, Peperoncino