Peel, clean and devein the shrimp. Take half of the shrimp and butterfly it open. If you prefer, you can do the same with remaining shrimp or leave as is. Rinse under cold water, keeping both separate. Place butterflied shrimp in a bowl. Pour 2/3 cup of fresh lime juice into the bowl. Stir well to combine, making sure shrimp is covered with lime juice. Cover and chill while you finish prepping.
Add the remaining shrimp to a saucepan of simmering water that has been salted. Cook for just 2-3 minutes or until shrimp turns pink and opaque. Drain immediately and place in in the refrigerator.
Prep vegetables. In a preheated dry skillet, toast the chile piquin for 1 minute. Transfer to the molcajete. Pour in 1/2 tsp of salt. Grind down as fine as possible. Grind the garlic and then the roasted jalapeno. Pour in remaining lime juice. Mix in the Worcestershire, maggi and salsa negra.
Pour the contents of the molcajete into the shrimp curing and chilling with the lime juice. Stir well to combine. Mix in the red onion, cucumbers and cilantro. Fold in the previously cooked shrimp. Stir well. Taste for salt. Adjust seasonings to your liking, including the three dark sauces.