marinated sliced lamb with sauce

Ingredients

• 12 pieces lamb (strips)
  
• 2 tablespoons ketchup
  
• 1 teaspoon brown sugar
  
• ¹/₂ teaspoon cumin
  
• ¹/₂ teaspoon dried coriander
  
• ¹/₄ teaspoon ground pepper
  
• 1 teaspoon dijan mustard
  
• 1 tablespoon soy sauce
  
• 1 tablespoon rice vinegar or apple vinegar
  
• ¹/₄ teaspoon lemon zest or lime zest
  
• 1 tablespoon butter
  
• 4 tablespoons lemon juice
  
• 1 cup water
  
• 1 pinch salt
  
• 2 tablespoons olive oil or veg oil
  
• 1 small minced onion
  
• 1 large minced clove garlic