- Pre-heat oven to 325 degrees. Heat water in pan big enough to hold banana leaves. (Disregard this step if using parchment).
- Rinse fish fillet with water, pat dry, and cut into 3-inch pieces. Cover chopped fish on plate and set aside in refrigerator.
- Remove center stem from banana leaves. Cut the two halves in half, creating four banana leaf pieces from each leaf.
- Soften banana leaves by dipping them in the pan of hot water for about 30 seconds. Remove leaves from water, wipe each piece dry, and set aside.
- Place onions, sweetened and unsweetened coconut, Serrano chili, cilantro leaves, mint, and coconut milk together in blender or food processor and blend until thick paste forms. Add a little water if paste is too thick to grind. Set aside.
- Heat 1 teaspoon of ghee with coconut oil in ovenproof saucepan over medium heat. Add cumin, coriander, garam masala, salt, and pepper to pan. Mix and sauté for 3−4 minutes. Add ginger and garlic and sauté for 2−3 minutes.Add blender mixture to saucepan and stir until well mixed. Cook for 5 minutes, or until sauce has re-thickened to a paste-like consistency. Turn off heat and set aside to cool.
- Place the banana leaf squares and fish on a flat work surface.
- Apply the paste from the saucepan liberally to both sides of each piece of fish. Sprinkle lemon juice on both sides of fish over paste.
- Place a piece of fish on each banana leaf and wrap up like a parcel. Tie parcel firmly with kitchen string. Repeat until all fish is secured in parcels.
- In a heavy frying pan, heat the remaining teaspoon of ghee over medium heat.
- Fry the banana leaf fish parcels together on one side for 2 minutes. Turn over and fry on other side for 3 minutes. Leaves will darken and shrink.** Cover pan and place in oven at 325 degrees for 5−7 minutes.
- Open parcels carefully and serve immediately.
**If using parchment, do not fry. Secure fish as indicated with twine and close tightly. Place packages in covered dish and cook in oven at 325 degrees for 8 minutes. Let sit for 2 minutes before opening parchment and serving.