Add the scallions, garlic, cucumber, yogurt, mint, olive oil, lemon zest, lemon juice and a little salt and pepper to a food processor or blender and puree using the pulse button to start and puree button to make smooth.
Taste and adjust seasoning with salt and pepper if needed.
Transfer to a container until ready to use. You can make this earlier in the day and store into the refrigerator until ready to use.