Mix water, flour, 1 teaspoon sugar, turmeric, and salt together in a bowl into a thick batter.
Heat oil in a large saucepan or fryer. Dip jackfruit into the batter and deep-fry until golden brown, 2 to 4 minutes.
Bring milk to a boil in a small pot; boil for 2 minutes. Add chocolate; stir until melted and smooth. Add 1 tablespoon sugar; stir until dissolved, about 1 minute. Simmer chocolate sauce over low heat, about 5 minutes.
Place fried jackfruit on a serving plate. Pour chocolate sauce on top.