Blanche jicama and carrots till soft. Drain off the water and add into the pan of sautéed onions and carrots.
Add in all the condiments, stir fry and mix well.
Assembly and frying
Lay a spring roll wrapper on a clean cutting board like a diamond. Put some filling (around 1 table spoon) on the bottom corner. Make sure it is not too close to the edge.
Fold the bottom corner over the filling and roll tight. Then, fold over the left corner. Ensure there are no air pockets.
Fold over the right corner, ensuring no air pockets. Then, roll the filling closer towards the top, making sure it is tight and without air pockets.
Once it looks like an open "envelope", use the cornstarch paste as glue and apply it on the edges of the top corner before rolling and sealing the spring roll completely.
Deep fry spring rolls over medium heat until golden brown.