Heat a large casserole filled halfway with oil. The trout must be able to fit in. On a large plate, mix flour with cumin. Dredge trout in flour, inside and out and deep-fry until golden brown, about 4 to 5 minutes. Season with salt.
For the zucchini cous-cous: In a saucepan on medium heat, coat with olive oil, sweat the onions, garlic, ginger and curry powder. Season. Add zucchini and saute for 3 to 5 minutes until soft. Check for seasoning. Keep on very low heat.
For the curry oil: In a small bowl, combine curry powder with salt and about 1/8 cup water to make a loose paste. Whisk in oil and let stand 1 hour to settle. Use the top, clear yellow oil. PLATING: Using a ring mold, cut out tuna fish can (both sides filed) or a small, oiled bowl, fill with half couscous then half of the zucchini. Place trout on top and drizzle with curry oil and garnish with scallions.