2 oz Tanqueray Gin
1 oz Vodka
5 mists vermouth
2 jalapeno-stuffed olives
Method 1 (preferred)
Add gin and vodka to martini shaker with a handful of ice. Shake until very cold, at least 60 seconds – a metal shaker will get hard to hold with bare hands. Strain into glass, add olives (plus a few drops of olive juice for a little saltiness). Apply five or six sprays of vermouth from an atomizer on top.
Chill gin and vodka in a freezer for at least three hours. Add measured amounts to glass, add olives and vermouth as above.
Method 3 (emergency use only)
If you have warm liquor and no martini shaker, fill glass about halfway with crushed ice. Add measured amounts of gin and vodka to glass, stir with a spoon, then add olives and vermouth as above.
I realize we all have slightly different palates and preferences, but I really don't understand people who use Bombay Sapphire or any other flowery gin in a martini. Like wine, different gins have varying levels of sweetness, and to me Tanqueray is the most bone-dry of them all. Bombay Sapphire is fine in a gin and tonic with a slice of lime. In a martini it's like standing next to a guy wearing too much cologne.
While being strict about the choice of gin, I have never been able to find much difference between vodkas, and I've done a lot of research on this topic. Use your favorite. Try a little experiment sometime: take a bottle each of Grey Goose, Smirnoff, and some local no-name vodka, chill in the freezer for a while, then do a blind tasting. See if you can tell which is which.
I use Noilly Prat vermouth because martini snobs seem to think it's the best so I bought a bottle about ten years ago. That's the last bottle of vermouth I've purchased. I don't use much vermouth.
I find shaking produces the best results, possibly because it beats up the gin and releases more of its botanicals, like tenderizing a steak. Or maybe it infuses tiny air bubbles that enhance flavour. A little melted ice may also to open up the liquor, the way scotch drinkers will add a drop or two of water to their dram. Many theories, but in practice it just tastes better.
A standard pimento-filled olive works fine, but the jalapeno really adds something unique. It's not very spicy, even when eating it at the end, and just seems to compliment the whole package. I usually just throw the olives in freestyle; you can put them on a toothpick or skewer if you feel the need. Do use green olives though. Using lemon, orange or cucumber to garnish a martini is like saying Roger Moore or Pierce Brosnan is the best Bond. It's olives and Sean Connery or nothing.
A waitress once asked me if I wanted my martini dirty, and to show her I knew what it meant I said yes right away. A dirty martini means with olive juice added, and I think they must have dumped in an ounce or two. That was disgusting. I like to dribble in a little brine when fishing the olives out of the jar with a spoon.
The atomizer is just a little sprayer, similar to a perfume bottle. When done right, the vermouth floats on top of the other alcohol like gasoline in a puddle. By atomizing you get more aroma than taste and both are subtle. But don't forget to add at least one spray, otherwise you're just drinking a big glass of gin.
Finally, the name comes from a line in the classic (and classical) Wayne and Shuster sketch, "Rinse the Blood Off My Toga", set in ancient Rome. Johnny Wayne plays Flavius Maximus, "Private Roman Eye", hired to solve the murder of Julius Caesar on, coincidentally enough, the Ides of March.
Flavius: Gimme a martinus.
Cicero the Bartender: Don't you mean martini?
Flavius: If I wanted two, I'd ask for them.