Yotam Ottolenghi and Lukasz Rafacz's Sumac Martini

For the sumac-infused vodka:

• 3 tablespoons sumac
  
• 1 bottle (750 ml) of high-quality vodka
  

For the sumac martini:

• 2 ounces (60 ml) sumac-infused vodka
  
• 1 1/4 ounces (40 ml) Velvet Falernum liqueur
  
• 1 3/4 ounces (50 ml) lime juice
  
• 1 1/4 ounces (40 ml) pomegranate juice
  
• A few pinches sumac, to garnish
  

1. To make the infused vodka, place the sumac in a large glass or ceramic bowl and pour over the vodka. Cover and set aside for 2 hours, stirring from time to time, then strain back into the bottle through a fine-mesh or muslin-lined sieve.
2. When ready to serve, place all the ingredients in a shaker with some cubed ice. Shake really hard for 10 to 15 seconds, then double-strain (through a strainer and into a fine-mesh sieve) into two chilled glasses. Serve at once, with a sprinkle of sumac on top.