Dry the shrimp/prawns with paper towels then chop each prawn into 2 - 3 pieces. In a bowl, season the shrimp/prawns with salt, black pepper, garlic powder, onion powder, chilli powder and dried oregano then set aside.
Place a frying pan on a medium - high heat then add in the butter. Once the butter has melted and sizzling, add the onions and cook for 2 minutes. Add the shrimp/prawns to the pan and continue to cook them with the onions for 1 minute while stirring.
Add in the chopped jalapeños and coriander and stir then add and mix in the tomato purée and lime juice. Once all the ingredients are combined and the prawns are cooked through, transfer the prawns to another container and set aside.
Lightly grease the same frying pan with butter and place on a low to medium heat. Add a tortilla then sprinkle 25g cheese on half the tortilla. Top with ¼ of the shrimp/prawn mixture then top the shrimp/prawns with another 25g of cheese.
Fold the tortilla and toast for 30 seconds. Turn the taco over and toast for another 30 seconds until golden brown. Transfer the taco to a plate and repeat the process with the rest of the tortillas.