A very simple but really delightful Greek technique for cooking fish. It works well with any firm-fleshed fish that will hold up to grilling, but I think it's especially good with swordfish steaks or tuna.
Brush fish with olive oil and lemon juice, sprinkle with salt and oregano. Let sit at room temperature while you light up the grill.
Grill fish 4-5 minutes on each side, or until done to your liking. I prefer to leave tuna somewhat rare inside, so it takes less time than other varieties.
Prepare latholemono by placing all ingredients in a blender, and blending until smooth and creamy. It will separate eventually, so make it immediately before serving. There will probably be leftovers. It can be whisked back together and used as a salad dressing or sauce for vegetables or other meats.