Add shallot to a medium bowl; cover with cold water and set aside while prepping remaining ingredients.
In a large bowl, whisk together olive oil, 3 tablespoons lemon juice, 1 teaspoon lemon zest, and 1 teaspoon salt.
Add tomatoes, cucumber, pepper, parsley, mint, dill, sumac, and Urfa pepper. Drain shallots and add to bowl; toss to combine.
Add feta and gently toss to combine; season with salt and lemon juice to taste.