With spring come changes -- and those changes are popping up like little flowers on cocktail lists across town, especially as mixologists switch up menus to include seasonal ingredients. At Williams & Graham, bar manager Jason Patz took us on a tour of some of the new and exciting concoctions available right now.

"This is one of Sam Johnson's cocktails," Patz says, filling a mixing glass with large cubes of ice. When we ask who Johnson was -- thinking he may have been one of America's storied barkeeps or mixological pioneers -- we learn that he's actually an employee of Williams & Graham. "He started out as a barback for us," Patz explains, and "he's been with us for a little over a year and a half, recently becoming a full-fledged bartender just in the past six to nine months."

As it turns out, the cocktail menu at Williams & Graham a very democratic project. See also: Williams & Graham bartenders Jason Patz and Ali Widdecombe finalists in USBG World Class battle

Johnson's addition to the cocktail menu is the Bardstown Baptist. As Patz describes it, the drink is, a black Manhattan -- a Manhattan in which the traditional sweet vermouth is replaced by a darker, more bitter spirit called an amaro.

The foundation of the Bardstown Baptist is Elijah Craig 12-year whiskey, to which Patz adds Cynar artichoke amaro. Cynar is an Italian bitter liqueur made from thirteen herbs and plants -- artichoke. It's as black as coffee, and gives the drink a dark hue.

Next, Patz adds Pierre Ferrand Pineau des Charentes. "This is typically served like a dessert wine," Patz explains, adding that its origin is the famous Cognac region of Southwestern France. "They take unfermented grape juice, add cognac or brandy to it, then they age it. It's a little sweet, low in alcohol, and it is a really nice little sweetening agent."

Patz grabs a tall, slender bottle. "After that, we have the Bitterman's Amere Nouvelle," he says. "It's like an orange bitters. So, we have two bitter elements and two sweet elements to balance everything out." Amere Nouvelle is a tart liqueur made from bitter oranges and gentian root.

Stirred over ice, the Baptist is strained over a large, hand-cut ice-cube, hewn by hand into a rough sphere. Next up: the Kuhio Bay. "This is Allison's drink," Patz says, smiling. It was created by Allison Widdicombe, a bartender at Williams & Graham who hails from Hawaii.

Patz sets up his metal cocktail shaker, rips a green leaf in half, and drops it in. The leaf, Patz explains, is from the Kaffir lime tree, native to Indonesia. The juice of this type of lime is too pungent to consume, but the leaves are popular in Thai cooking. The dried leaf looks and feels like a bay leaf; flavors range from lime to lemongrass.

To this, Patz adds lime juice, lychee puree and a spoonful of green powder. "This is matcha powder," Patz says. "I picked this up today at an Asian market downtown. Basically, it's powdered green tea leaves."

After slipping an egg white into the mix, Patz adds ice and shakes vigorously. "The ice pulverizes the lime leaf," he notes. The bruising of the leaf brings out more of its flavor. Patz empties his mixing tin into a cocktail glass, revealing a bright green cocktail with a thin layer of white foam floating on top.

The taste is tropical, exotic, Asian. The egg white, also beaten thoroughly, adds body, making the drink feel a bit thicker than it looks. The first sip is refreshing: The green tea powder and lime leaf definitely make the Kuhio Bay a bright and clean warm weather cocktail.

Keep reading for one more spring cocktail at Williams & Graham. Patz gears up for the third and final cocktail of his spring menu showcase, the Garden Party 2.0. The first version appeared on a previous menu, but this one requires some intriguing equipment. Into a clear plastic tumbler, Patz pours Spring44 gin, celery and cucumber juice, black pepper, coriander, lemon juice and sugar and ice. He then caps the tumbler, and shakes it.

What happens next is amazing: Patz brings a carbon dioxide cylinder out from behind the bar, hooks it up to a little spout on the tumbler, and blows gas right into the tumbler. "This carbonates the drink," he says, while shaking it a second time. It takes only a few seconds. As he pours the ingredients over fresh ice, the bubbles come right up to the rim of the glass. The drink is spicy and refreshing, and the bubbles make it perfect for a celebration of springtime.

Williams & Graham is open daily from 5 p.m. until 1 a.m. Find more information here.

• Booze