Blackcurrant Vermouth

Ingredients

• • 1 rosemary sprig, leaves roughly chopped, plus more for serving
  • 1 oz (30 ml) crème de cassis
  • 2 oz (60 ml) apple vermouth
  • 1 tsp (5 ml) lemon juice
  • 2 tsp (10 ml) egg white (see note)
  • 3 drops aromatic bitters (Angostura-type)
  • 1/2 cup (125 ml) ice cubes
  • Ground sumac (optional)