First, marinate the shrimp. In a gallon-size resealable bag, combine all of the shrimp marinade ingredients. Place in refrigerator to marinate for about an hour.
As shrimp is finishing up marinating, preheat oven to 425 degrees Fahrenheit. Season cast iron skillet with 1 tablespoon olive oil and ¼ teaspoon salt.
In a medium bowl, toss potatoes with 1 ½ tablespoons olive oil. ¼ teaspoon salt, ¼ teaspoon pepper, oregano, dill and shallot. Pour into seasoned cast iron skillet.
Place skillet in preheated oven and cook for 10 minutes.
After 10 minutes, add peppers and shrimp. Cook for another 10 minutes.
Finally, add crumbled feta and cook for another 5 minutes. After 5 minutes, turn the oven to a Hi broil and broil for an additional 3 minutes, or until feta is golden. Remove from oven.
Once skillet has cooled slightly, add tomatoes and cucumber. Serve with torn pita bread, if desired.