Make the dressing first to allow the flavors to meld. In a small bowl, combine 3 Tbsp mayo, 4 Tbsp sour cream, pressed garlic clove, ¼ cup chives, ⅛ tsp black pepper and ¼ tsp salt (or season to taste). Stir together then add 1 to 2 Tbsp milk, or add milk to desired consistency. Cover and refrigerate until ready to use.
In a large mixing bowl, combine lettuce, tomatoes, bacon and croutons. Just before serving, drizzle with dressing (adding it to taste) and toss to combine.
