Somewhere between a sour and a smash. I use Gordon Graham's Black Bottle Blended Scotch Whisky, blended from Islay malts. It's nowhere near as mouth-shaking as Laphroaig or Caol Ila, just pleasantly smoky. I've made this drink with Jameson instead on a whim and while it technically works it's better with some smoke to fight the pepper. If you can't find Black Bottle I'd say you could get away with some boring Highland with a barspoon of Laphroaig thrown in.
2 chunks lemon
0.5oz simple syrup (I like 1/2 demerara and 1/2 white sugar)
2oz Black Bottle Scotch Whisky
4 drops black pepper tincture
3-4 drops Fee's Old Fashion (or 6-8 Angostura)
Muddle the lemon and the syrup in the bottom of the tin. Add ice, whisky, tincture, and bitters. Shake, double strain onto rocks. If you're classy you'll probably garnish with a swath of lemon. I guess I'm not classy.
(as for the black pepper tincture - I use Wild Turkey Rye 101 and whole black peppercorns, 1tbsp of pepper for each oz of rye. Soak overnight, remove peppercorns. Done.)