Begin by preparing your ingredients. Peel the saba bananas (saging na saba) and cut each one lengthwise into two halves. The bananas should be ripe but still firm (hinog pero matigas pa) to hold their shape. Pat the sweetened jackfruit strips dry to prevent oil splatter during frying.
Set up your rolling station with spring roll wrappers (balat ng lumpia), prepared bananas, jackfruit strips, and granulated sugar (asukal). Keep the wrappers covered with a damp cloth (basang tela) to prevent them from drying out.
For assembly (pagbabalot), place a wrapper in a diamond position on your work surface. Roll a banana piece in sugar, then place it near the bottom corner of the wrapper along with 2-3 pieces of langka. Fold the bottom point over the filling, then fold both sides inward. Roll tightly upward, sealing the edges with water. Roll the wrapped turon in additional sugar for caramelization.
Heat canola oil (mantika) in a deep frying pan or kawali to 350-375°F (177-190°C). If you don't have a thermometer, test the oil by dropping a small piece of wrapper - it should bubble immediately and rise to the surface.
Fry the turon in batches, seam-side down first, for 3-4 minutes or until golden brown and caramelized (hanggang maging gintong-brown at caramelized). Maintain steady oil temperature for even caramelization. Don't overcrowd the pan as this will lower the oil temperature.
Remove from oil using tongs and place on a wire rack (hindi sa paper towel) to drain and maintain crispiness. Never stack hot turon to keep them crispy. Serve immediately while hot and crunchy, optionally with vanilla ice cream or a sprinkle of powdered sugar.