Add shrimp to bowl with canola oil, salt, pepper, and Mexican seasoning & toss to coat
Cover the shrimp and place in refrigerator to marinate for 30 minutes
Set grill to 450°
Roast the Poblanos, peel skin, seed, and dice
Add cast iron skillet to grill to begin heating up
Add onions, bell peppers, and Poblanos to skillet with ¼ stick butter
Cook down the onion mixture; about 7 minutes and remove from direct heat
Add shrimp to skewers and place on grill over direct heat
After about 1.5 minutes, flip and begin basting the shrimp with the melted butter until done cooking 1.5 minutes per side; 3 minutes total
Remove shrimp from skewers and set aside
In large skillet place a couple tortillas down and add cheese to one side
Place 3 shrimp on top of the cheese then top the shrimp with the onion mixture and 1 tsp of cilantro
Let the tortilla set for about 30 seconds then flip the other side over the top of the shrimp to make a taco
Press down on the taco to get the cheese to touch bothsides, this will keep the taco closed
Repeat the previous 4 steps for the other tacos