Put lavender on top of an inverted cocktail shaker. Add Angostura bitters to a small, clean spray bottle (available at drugstores). Spray the bitters over the lavender 6 times, simultaneously flaming the misted bitters with a lit match. Add the lavender to hot water and let steep for 15 minutes; strain into a small bowl and stir in honey. The syrup can be refrigerated for up to 3 weeks.