Slit the calamari tubes up 1 side and lightly score 1 side. Place the tubes and tentacles in a bowl and add the lemon zest, lemon juice, garlic, olive oil, oregano, salt and pepper and toss to combine. Refrigerate for 30 minutes.
Preheat a grill pan on high heat.
Remove the calamari from the refrigerator and place on the grill in batches for 1 1/2 to 2 minutes per side. Cut the tubes into strips and leave the tentacles whole. Before serving, sprinkle with lemon juice and chopped parsley.
Recipe courtesy of Dan Smith and Steve McDonagh