Step 1

Make the sauce: In a blender, place the cilantro, scallions, serrano peppers, mayonnaise, lime juice, olive oil, garlic, vinegar and salt and blend on low to combine, then increase to high and blend until smooth. If the sauce is too thick, add water, 1 tablespoon at a time, until it reaches the desired consistency. Taste, and season with additional salt, if needed. You should have a scant 1 cup.

Step 2

Make the salad: Halve, pit and peel the avocados, and place the flesh of 1/2 avocado onto each of the 4 serving plates; mash it with a fork. Top each with 1/4 cup each corn and tomatoes, and some of the red onion, then drizzle with the lime juice and sprinkle with salt.

Step 3

Place 4 to 5 shrimp on top of each mound, then spoon the sauce over and serve.