If you like to experiment with citrus, try hunting down a fresh yuzu. It’s the only cirtrus that can grow this far north, and Wade Bennett at Rockridge Orchards sells the hazardously thorny plants for home gardens (he suggests that when planted under bedroom windows, they make an excellent deterrent to teens who might be tempted to sneak out). Add a few ounces of yuzu juice to the orange juice at the end of its reduction time, and the orange syrup will have an extra kick of light acidity.