Combine the marinade ingredients together and add the shrimp. Marinade for 30 minutes.
Mix the ingredients for the Mexican cream and set aside.
Heat a separate dry cast iron skillet over medium high heat. Toast the tortillas, one at a time, until they smell toasted and a couple brown spots have developed (that means they are done). Remove and set aside.
Drain the shrimp and pat as dry as possible.
Heat the butter in a skillet over medium high heat. Add the shrimp (do this in 2 batches) and quickly cook for about 1-2 minutes, or until the shrimp is pink (means it is cooked through).
Remove and cook the second batch.
Serve the shrimp on the toasted tortillas with the Mexican crema, salsa, cilantro, fresh lime, and cotija cheese.
Notes
Use medium or large raw shrimp for the best result - jumbo shrimp can be hard to eat in a taco.
Don't crowd the pan - cook the shrimp in 2 batches to ensure they brown instead of steam in the pan.
Pat the shrimp dry before adding to the pan to help them brown faster. Otherwise, they steam instead of brown so you won't get that nice crust.
Make the crema while the shrimp is marinating so it is ready when the tacos are ready.