Start by peeling, deveining, and slicing each shrimp in half lengthwise. Place the shrimp in a large glass or ceramic bowl. This method helps the shrimp “cook” more quickly in lime juice by increasing the surface area.

Juice all 20 limes and pour the juice over the shrimp. Ensure the shrimp are nearly submerged—if needed, add a splash of cold water. Gently stir, cover, and refrigerate for 30 to 40 minutes. The shrimp will turn opaque and firm as the acid “cooks” them.

While the shrimp is marinating, bring a small pot of water to a boil. Add the tomatillos and simmer for 5–6 minutes until soft. Drain and let cool. Boiling reduces bitterness and helps them blend smoothly.

In a blender, combine the boiled tomatillos, 3 serranos, 4 jalapeños (remove seeds if desired), garlic, and cilantro. Blend until smooth and vibrant green. This creates the bold, spicy backbone of your aguachiles.

Once the shrimp is fully “cooked,” pour the green sauce over them. Mix gently to coat. The color will pop immediately and the aroma will be spicy and herbaceous.

Stir in sliced red onions, cucumbers, and the remaining sliced jalapeño. Carefully fold in the avocado cubes last so they don’t get mashed. Season generously with salt to bring out all the flavors.

Refrigerate the finished aguachiles for another 20 minutes to let all the flavors meld. Serve cold on tostadas or crackers for a crunchy contrast to the juicy shrimp.