When you’re looking for a bar refresh, it’s easy to think big, with new bottles of spirits and liqueurs. Or even medium size, finding new mixers and juices to spruce up your cocktail game. But when was the last time you thought small? Like, really small: tiny bottles of bitters.

For something so little in volume, bitters can have a truly outsized effect on cocktails; just a few drops can transform the profile of a drink. Could you get by without it? Purists might cringe—iconic cocktails such as the Old Fashioned, Manhattan and Sazerac are defined in part by the addition of bitters—but yes, probably.

But would you want to? “Think of bitters as if they’re your liquid spice shelf,” says Ashley Duval, an ethnobotanist and co-author of Botany at the Bar: The Art and Science of Making Bitters. “Some might say that you only need salt, pepper and turmeric while cooking but then you’re neglecting this whole world of flavor—and the same holds true with bitters.”

Duval and her co-authors, Selena Ahmed and Rachel Meyer, all met while pursuing degrees in ethnobotany in New York and collectively turned their scientific know-how into Shoots & Roots Bitters, a small-batch bitters company. The book came next, with the goal to demystify the often secretive and opaque bitters-making process.

“We want to celebrate transparency as a way to get people excited about botany,” says Ahmed. “We want to inspire others to begin to think about what’s growing in their own landscape. By tapping into local plants, you have more of a connection to what you’re experiencing in a drink.”

Duval says bitters are usually made from a bittering agent (mugwort, gentian, dandelion root or licorice), which is then masked with a combination of other flavors, such as cloves, anisole and other flavorings. For all the secrecy, the actual process of making bitters isn’t that complicated. As the three explain in their book, you can DIY your own version at home by grinding spices and botanicals, adding that to a high-proof spirit and letting it sit for a few weeks, straining out the particulates and reserving the alcohol. They also recommend making an additional infusion by boiling the discarded botanicals in water and straining again, adding the water infusion to the alcohol infusion.

If you’re not quite up to setting up a lab in your kitchen, there is a wealth of offerings on store shelves. If you are looking to build out a basic bar, just Angostura bitters would be enough. For a more complete classic bar, you might add orange or Peychaud’s Bitters. And from there, you should go where your heart leads. An easy rule of thumb: Chocolate and spicy bitters tend to pair well with aged spirits, while more floral and fruity options layer well with lighter spirits, such as gin or vodka.

Brands such as Bittermens and Fee Brothers tend to be among bartender favorites, but don’t be afraid to seek out regionally-themed options to incorporate local flavors—they can make a great gift if you’re travelling, too.

Here are some basic templates for recipes that will let your new purchases shine:

BITTERS AND SODA

Serves 1

This refreshing spritzer is perfect for hot summer afternoons and can easily be made without the alcohol if you’re looking for a fun mocktail.

• 2 to 3 dropperfuls of any bitters
• 4 ounces sparkling water
• 2 ounces fresh juice (optional)
• 2 ounces gin or vodka (optional)
• sweetener to taste, such as maple syrup, honey, sugar syrup, agave or stevia

• garnish: lemon or lime wedge
In a highball glass, add the bitters, sweetener, juice (optional) and alcohol (optional), and stir to combine. Add ice, then the sparkling water. Garnish with a lemon or lime wedge.

BITTERS AND WHISKEY

Serves 1

This play on the Old Fashioned gives you lots of room to experiment. Try a chocolate bitters for an after-dinner drink or something spicy as a pick-me-up. The sweetener can add plenty of flavor, too: honey and maple syrup will add a rich texture, while simple syrup will let the flavor or the whiskey (or bitters) shine through.

• 2 to 3 dropperfuls of any bitters (Angostura is the classic choice)
• sweetener to taste, such as 1/4 ounce maple syrup, honey, sugar syrup, agave or stevia

• 2 ounces whiskey (optional)
In a rocks glass, add the sweetener and bitters and stir to combine, adding one barspoon of water if needed. Add the whiskey and stir. Add 3 to 4 ice cubes and stir until chilled. Garnish with an orange twist (if appropriate).
Recipes adapted from barconventbrooklyn.com