Heat the oil in a large skillet over high heat. Dust the tuna with the flour, patting off any excess. Saute the tuna in the hot oil, briefly, on both sides; remove the tuna to a plate and set aside. Add the onion, garlic and ginger to the same hot pan and saute for a minute or two. Stir in the chili powder, cumin, turmeric, salt and pepper; saute for another minute. Add the tomatoes, wine, and lemon juice, scrape the bottom of the pan for any particles that may have adhered there. Add the tuna back into the pan with the tomato sauce. Bring the mixture to a boil, then lower it to a simmer. Cover the pan and cook the fish for five minutes.
