Gently muddle 6 to 8 mint leaves with 1⁄4 ounce of the ginger syrup in a julep cup. Insert a soda straw into the cup and fill the julep cup to just below the rim with crushed ice. Combine bourbon, amaro, and remaining 1⁄4 ounce ginger syrup in a mixing glass, stir, and strain slowly over crushed ice. Dome additional crushed ice over julep cup. Express lemon peel over ice and discard. Remove the soda straw and insert mint sprigs into the shaft from the straw. Place two cocktail straws on the opposite side of the cup from mint.