Prepare the filling by combining the flaked tuna, grated coconut, onion, green chilies, curry leaves, ginger, black pepper, salt, and lime juice in a bowl, mixing until everything is evenly combined. In another bowl, mix the flour and salt, then gradually add warm water and knead until you have a soft, smooth dough. Add the oil and knead briefly, then cover and let the dough rest for 10 minutes. Divide the dough into small portions and roll each one into a thin circle. Place a small spoonful of tuna filling in the center, fold the dough around it, and carefully pinch and seal the edges to create a small oval or round pastry. Heat vegetable oil over medium heat and fry the gulha in batches until they become crisp and golden brown on all sides. Transfer them to a paper-lined plate to drain excess oil and serve warm with tea or your favorite dipping sauce.