Rinse the rice thoroughly and soak it in water for at least 2–3 hours, or until the grains become soft enough to crush easily. Drain the rice well, then grind it into a coarse paste, adding a little water if necessary. Transfer the rice mixture to a large bowl and add the flaked tuna, grated coconut, chopped onion, green chilies, curry leaves, ginger, turmeric, black pepper, salt, and lime juice. Mix everything thoroughly until you have a thick, evenly combined mixture with a slightly coarse texture. Grease a baking dish with vegetable oil and spread the mixture evenly into it, pressing it down firmly with the back of a spoon. Bake in a preheated oven at 180°C (350°F) for approximately 35–40 minutes, or until the surface is firm and lightly golden. Allow the boakibaa to cool for a few minutes before cutting it into squares or diamond-shaped pieces and serving.