Place the calamari in a bowl and pour in enough milk to fully cover it (about 1 cup). Let it marinate for at least 15 minutes.
In a separate bowl, mix the flour, cornstarch, dried dill, salt, and pepper.
Take a handful of calamari, letting any excess milk drip back into the bowl, then add it to the seasoned flour. Toss until evenly coated, then transfer to a baking sheet.
Heat oil to 375°F (it will drop below 350°F when the calamari is added). Fry two handfuls at a time for 2–3 minutes, until golden brown and crispy. Transfer to a paper towel-lined plate and repeat with the remaining calamari.