Heat skillet or griddle over medium heat. Drizzle olive oil and place fish onto griddle or skillet. Cook until fish reaches an internal temperature of 145º F. Remove and allow to rest for about 3 minutes before cutting into large pieces for tacos.
As fish is cooking, mix together sour cream or Greek yogurt with Sriracha sauce in a small bowl.
To assemble fish tacos, layer lettuce or cabbage greens inside the middle of a flour tortilla. Then add pieces of cooked white fish, spoon on Sriracha cream, then top with pico de gallo. Serve with a wedge of lime to be squeezed over fish taco before eating.