Heat 1 tablespoon of the oil in a large skillet over medium heat. Season shrimp with salt, pepper and oregano. Place shrimp in hot pan (or stove-top grill pan) and cook 2 minutes per side, until opaque and cooked through.
Meanwhile, in a medium bowl, combine mayonnaise, chives, gherkins, and lemon zest. Mix well and season to taste with salt and pepper.
In a large bowl, combine ditalini, remaining olive oil, peppers, parsley, and vinegar. Toss to combine and season, to taste, with salt and pepper. Serve the ditalini salad with 1 1/4 pounds of the shrimp and all of the tartar sauce. Reserve extra shrimp (about 1/2 pound cooked) for another meal.