In a large bowl, whisk together the 1/4 cup oil, lime, cilantro, cumin, coriander, salt, and Tobasco until emulsified. Add shrimp, corn, cheese, avocado, tomato, and additional salt and Tobasco if desired, toss to coat. Cover and chill while preparing the tortillas. Heat the 1/2 cup oil in a skillet to medium. (The higher the heat, the more splattering, so lower the temp if needed.) Cook one tortilla at a time, a minute or so on each side, and as you remove each to a paper towel lined plate, fold it in half so that it cools in the shape of a taco shell. Stuff with filling and serve.