Peel and devein the shrimp. Rinse with cold water.
Carefully slice the shrimp into 1-inch pieces.
Swiftly season the shrimp with Old Bay seasoning and onion powder. Let it sit for a bit.
Heat the cooking oil in a skillet. Add half of the cilantro, tomatoes, and chopped onion.
Add the shrimp and mix well. Stir occasionally to prevent burning, and flip the shrimp every once in a while to make sure both sides are cooked.
Cook until the shrimp turns golden, which should take a few minutes.
Remove it from the heat and set it aside.
Heat oil in another skillet and fry the corn tortillas.
Fry the tortillas one at a time. Keep a constant eye on the pan so as not to burn.
Once they become soft, which should only take half a minute, gently fold them to make a taco shell.
Once the tortillas are done frying, remove them from the heat and transfer them to a serving plate. Drain the excess fat with a paper towel.
Cut the avocado in half and remove the pit. Scoop out the flesh carefully.
Mash the avocado gently, so that it is a bit chunky.
Add onion powder, lime, green onions, avocado, salsa, and salt in a mixing bowl. Also add the other half of the chopped onions, tomatoes, and cilantro.
Mix well until combined.
Fill the taco shells with guacamole, shrimp, and sour cream.
Top with Mexican cheese.