I'm reading 'The Tequila Ambassador' by Tomas Estes (highly recommended). I met him once at a tasting organised by The London Cocktail Society where he pulled out a bottle of his (then) soon to be released Curado. It was delicious. Anyway, he (or possibly @thecocktailgeek) stated that if you take a gin cocktail and swap the gin out for tequila you will invariably have a great (or even better) drink. So this is my take on the martini. The sherry stands up better I think to the tequila than a vermouth.
2 shots Tapatio Blanco tequila
1/2 shot Manzanilla Sherry
Bittermen's Hopped Grapefruit Bitters
Stir over ice, strain into chilled coupe. Express zest over, rub around rim and drop into drink.