In a medium-size bowl, whisk together sour cream, mayonnaise, lemon juice, garlic powder, and Worcestershire sauce. Add-in crumbled blue cheese, chives, and pepper. Stir. Add-in 1 tablespoon at a time of Half and Half to thin dressing to desired consistency. Taste and adjust seasoning with salt and additional pepper.
Store in an airtight container or jar in the refrigerator for up to one week.