Traditional Greek gyros are made of spit-roasted lamb cut into chunks and wrapped in a warm round of pita then drizzled with tzatziki. Mine is definitely a California version, low in carbs, much lighter and even messier than the original. Instead of lamb, I use spicy halibut fillets, and instead of bread, I serve the fish in crunchy lettuce cups. You can grill or bake the halibut. Set out a long platter with the halibut-filled lettuce cups next to a big array of condiments. Your guests can dress their gyros however they please. Be sure to pile a large stack of napkins on the table too.
1. Preheat the grill to medium-hot or the oven to 350F.
2. For the Halibut: In a baking dish big enough to hold the fillets in a single layer, combine the 2 tablespoons olive oil, lime juice, chili powder, cumin, cayenne, salt and pepper. Add the halibut fillets and turn to coat thoroughly with the marinade. Let the fillets marinate for 10 minutes to absorb the flavors while you make the tomato salad.
3. For the Tomato Salad: In a medium bowl, mix the tomatoes, onion, olives, oregano, parsley, olive oil, and lime juice. Season with salt and pepper to taste and mix well. Set aside.
4. To Grill the Halibut: To prevent the fish from sticking, brush the filets with a little olive oil before placing them on the grill. Cook the fillets until they begin to turn opaque on top, 3-6 minutes. (For halibut steaks, grill a few minutes longer, 5-7 minutes.) Using a long-handled spatula, turn the fish carefully and grill on the second side for 3-6 minutes until the fish is opaque throughout.
5. To Bake the Halibut: Pour 1 tablespoon olive oil into a large skillet over high heat and sear the fish for 1 minute on each side. Bake the fish in an oiled Pyrex baking dish in the oven until it is firm to the touch and flakes easily when separated with the tines of a fork, 10-12 minutes for fillets and 12-15 minutes for steaks. When the fish is done, remove it from the oven and let it rest in the pan while you set up the lettuce cups on a large serving platter.
6. For the Lettuce Cups: Form the lettuce cups by gently separating the heads of butter lettuce and radicchio. Make a cup by lining a whole leaf of butter lettuce with a radicchio leaf. Flake a generous portion of fish into each lettuce cup, or cut the fish into small chunks and divide evenly among the lettuce cups.
7. Top with the tomato salad. Drizzle with Avocado Tzatziki (see separate recipe), if desired, and garnish with the pepperoncini and scallions.