If you want to find a good drink in Portland, all you have to do is step outside and turn left or right. This Oregon city is full of great bartenders. So many, in fact, it’s not easy for a maker of fine drinks to stand out. Brandon Lockman, head bartender at Red Star Tavern & Roast House, stands out.

Red Star has the biggest whiskey selection in town (around 75), so Lockman is partial to whiskies, ryes and bourbons, as you’d expect. And like most better barkeeps, he makes his own tinctures, barrel-aged cocktails and experiments with cocktail vinegars. But what he’s doing with ice is what’s drawing attention.

Lockman played around with the alcohol-to-water ratio and found a perfect combination to obtain a frozen alcohol ice cube. He calls them “boozy cubes.” For a Manhattan, he’ll freeze sweet vermouth and bitters and then place the cube in bourbon. As the cube melts, it slowly becomes a Manhattan. Nobody likes watered-down drinks, so this is a fantastic solution.

Lockman has taken his boozy cubes a step further by dropping one made of Campari or Aperol into a Manhattan. As the cube melts, the drink evolves into a Boulevardier. Not bad for a guy who began working at Red Star nearly 10 years ago as a busser while attending Portland State University.

Lockman regularly proves he is not a one-trick pony. On the opposite end of his boozy cubes is a drink he calls Nutty Woodford, which consists of Woodford Reserve and Nocello walnut liqueur. It’s served in a snifter, which, when presented to a customer, rests on a cup full of hot water to keep it warm.

And it’s not all about whiskey with Lockman. Consider, for example, a drink called Willamette Weak Sauce, which appears on Red Star’s happy hour menu. In this drink he marries gin, Dolin blanc vermouth, lemon, orange blossom honey and Serrano syrup. It’s a beautifully balanced combination of tart, floral and acidity with a touch of heat.

“It’s become a passion of mine to master old techniques and seek out new ones,” says Lockman. “It keeps me on my toes.”

Here’s Lockman’s recipe for making Manhattan-flavored ice cubes:

Mix 1 oz. of sweet vermouth and a few dashes of Angostura bitters per each segment of a super-sized ice cube tray. Top with water to fill tray. Freeze the cubes overnight. The ice won’t be rock-solid, but it won’t be slushy, either. If you don’t have a tray for super-sized cubes, Lockman suggests you mix water and vermouth in a 2:1 ratio, and then pour into your usual tray and freeze.