This cocktail is refreshing and just complex enough. It tastes great even without the alcohol but can also stand up to a strong pour, so you can control how boozy it is as the mood strikes. You'll have extra herb syrup, which will keep tightly covered in the fridge for a couple of weeks. Make more cocktails or try using it to sweeten a sophisticated lemonade.
In a small pot, combine the thyme, rosemary, sugar and water. Set over medium-high heat and simmer, stirring occasionally, until sugar is dissolved and liquid is just shy of boiling. Remove from heat and set aside for at least 30 minutes. The longer it sits, the stronger the herb flavor will be. Strain the liquid into a little cup or container and discard herbs.
When ready to serve, fill two medium glasses about 2/3 with ice. Juice the citrus into a liquid measuring cup with a spout and stir in two tablespoons of the herb syrup. Divide between glasses, garnish with herb sprigs and blood orange slices if you like, and serve immediately.