Dust the top of the fillet with 1/4 teaspoon salt, the cayenne, the turmeric, and lots of black pepper. Pat the spices in. Cover and refrigerate from 1 to 6 hours.
Preheat the oven to 500F.
Lay the fish out on a baking tray, skin side down. Combine the oil, melted ghee or butter, lemon juice, cumin, and 1/4 teaspoon salt in a small bowl and mix well. Spread this evenly over the top of the fish. Scatter the thyme sprigs over the top as well and place in the top third of the oven. Bake, brushing frequently with the juices, until the fish turns opaue all over, 25 minutes or less, depending on the thickness of the fillet.
Mix together in a small bowl the garlic, ginger, cumin, thyme, black pepper, cayenne, paprika, garam masala, turmeric, lemon juice, sugar and salt. Put this paste on both sides of the fish pieces - it will adhere better to the fleshy side - and set aside for 30 minutes.
Put 1 tablespoon of the oil in a non-stick frying pan and set on medium-high heat. When hot, put in half of the fish pieces, flesh side down, and cook for about 2 minutes or until nicely browned. Turn over and brown the skin side for another 2 minutes. Remove to a dish and leave in a warm place. Quickly wipe the pan out with a paper towel, put in the remaining 1 tablespoon oil, and cook the rest of the fish the same way.
Tandoori-Style Striped Bass Fillet
One of the characteristics of tandoori fish in the Punjab, where tandoori - or clay-oven baked meat and fish dishes originated, is that they are flavoured with ajowan seeds. These tiny seeds look rather like small celery seeds, except that their main aroma comes from thymol, which you find in thyme as well. Instead of using ajowan (ajwain in India), I have simplified matters by using the more easily available thyme instead.
Serving suggestions: For a very light meal, you can serve this fish with a salad. You could also make a more substantial meal by offering some rice and either Spinach with Garlic and Cumin or Swiss Chard with Ginger and Garlic.