Peruvian Aji-Style Sauce

[Chowhound]

1 head romaine lettuce, stem-end trimmed and discarded
½ bunch fresh cilantro, stems removed
5 eaches green onions
¼ cup mayonnaise
2 medium jalapeno peppers, seeded
1 clove garlic
salt and ground black pepper to taste

Place romaine lettuce, cilantro, green onions, mayonnaise, jalapeno peppers, garlic, salt, and black pepper into a blender; blend until smooth, about 2 minutes.