In a blender or food processor, combine the mayonnaise, sour cream, buttermilk, ranch dressing mix packet, chopped cilantro, minced garlic, chopped jalapeños, and lime juice.
3/4 cup sour cream, 1/4 cup mayonnaise, 1/4 cup buttermilk, 1 packet ranch dressing mix packet, 1 to 2 fresh jalapeños, 1/4 cup fresh cilantro, 2 cloves garlic, 1 tablespoon fresh lime juice