1. In a skillet, heat 1 tbsp vegetable oil and fry ginger and garlic until fragrant.
2. Add chicken, leek and brown mushrooms and fry them until chicken is no longer pink. Add all the ingredient A and stir to season.
3. Add katakuriko/potato starch (dissolved in water) to thicken the mixture. Let it cool to room temperature.
4. Lay a spring roll wrap flat, tip down. Place the filling mixture centered in the lower tier of the wrap. Roll up tightly. Dab a little 'glue' mixture along the edges to seal. Repeat until you finish the filling mixture.
5. Pour enough oil in a wok or large saucepan and heat on medium-high until hot : Stick in a bamboo chopstick, if bubbles appear, it's hot enough :-). Place the rolls gently in the oil and cook both side, turning occasionally, until nicely and evenly golden. Transfer them to a plate lined with paper towels to drain the excess oil.