Lemongrass Beef Marinade

• 2 lbs. sirloin tip, cut in 1/8" thick slices
  
• 1/2 cup peeled fresh lemongrass, chopped
  
• 1/3 cup shallots, chopped
  
• 1 tablespoons Vietnamese fish sauce (otherwise known as "Nuoc mam" or "Mam pla")
  
• 1 tbsp soy sauce
  
• 1 1/2 tablespoons sugar
  
• 2 teaspoons olive oil
  
• 6 medium garlice cloves, smashed
  
• 2 serrano chiles, seeded and chopped
  

(Alternately, 2 tbsp fish sauce & no soy sauce.)