Chop cilantro: Place cilantro in a food processor or mini food processor; pulse until finely chopped, about 10 times.
Chop peppers: Add pickled jalapeños; pulse until finely chopped, 8 to 10 times.
Add remaining ingredients: Add sour cream, mayonnaise, ranch dressing mix, lime juice, salt, and garlic; process until well combined, 20 to 30 seconds.
