Gin Rocket Cocktail with Fennel and Lime

Using a mandoline or vegetable peeler, thinly slice enough of the fennel bulb to yield 1/4 cup (about 1/2 small bulb). Add a pinch of the fennel fronds to a cocktail shaker along with sliced fennel and arugula leaves. Add lime juice and simple syrup and muddle until the fennel is bruised. Add gin and fill with ice. Shake vigorously until chilled, about 12 seconds. Double-strain into a chilled coupe glass and garnish with lime wheel, arugula leaf, or nasturtium if desired.