Build the Base: In a large mixing bowl, add the sour cream, mayonnaise, and an initial 1/2 cup of buttermilk.
Add the Aromatics: Add the finely chopped chives, parsley, and dill. Use a microplane to grate the garlic clove directly into the bowl.
Season & Brighten: Add the salt, black pepper, and a fresh squeeze of lemon juice.
Emulsify: Whisk everything together vigorously until the mixture is completely smooth and the herbs are evenly suspended.
The Consistency Check: Lift your whisk to check the thickness. If you prefer a thinner, drizzle-friendly restaurant consistency, continuously whisk while streaming in a little more buttermilk until you reach your desired texture.
Store & Chill: Transfer the ranch to an airtight deli container with a lid. While you can eat it immediately, the flavors are best after chilling in the fridge for 12 to 24 hours.