Method

1. To make the green sauce, place the parsley, scallions, garlic, anchovy fillets, basil, capers, and oregano in a food processor and pulse to chop and blend together.
2. With the motor still running, pour in oil. Add the lemon juice to taste, then process again.
3. If the sauce is too thick, add a little extra oil. Transfer to a bowl, cover and let chill in the refrigerator until needed.
4. Place a cast-iron griddle pan over high heat until you can feel the heat rising from the surface.
5. Brush the tuna steaks with oil and place, oiled side down, on the hot pan and cook for 2 minutes.
6. Lightly brush the top side of the tuna steaks with a little more oil. Use a pair of tongs to turn over the tuna steaks, then season with salt and pepper to taste.
7. Continue cooking for an additional 2 minutes for rare or 4 minutes for well done.
8. Transfer the tuna steaks to serving plates and serve with the green sauce spooned over, accompanied by lemon wedges.