Lovely if you're in the mood for salty and strong. I've always made with vodka but you can try with gin too. Highly recommend Losado Gordal pitted olives for the brine and garnish. The right amount of olive brine is crucial here and is really a personal preference. I'd recommend starting with 1/2 oz of olive juice, stir, and if it's not enough, add another 0.25oz. Or if you like it only slightly dirty, start with 1/4 oz and up it from there. The rinse of dry vermouth is optional here, some would think it doesn't belong, others that it's not a martini without it.