Place the chilis, shallot, water chestnuts, basil leaves, mint leaves and ginger in a large food processor. Blitz until the mixture resembles mulch. Set aside.
Place the chicken in a large bowl, add the chili mixture and the cornstarch. Pour the lime juice, fish sauce, kecap manis, and soy sauce over top. Add an ample amount of fresh ground pepper and using a clean hand, mix until a cohesive mixture forms. Cover and set aside.
Take a sheet of the spring roll pastry and lay it flat on a cutting board in a diamond formation. Place a large basil leaf in the center. Take roughly 2 tablespoons of the chicken mixture and form it into a log. Lay it across the basil leaf. Fold the corners of the sheet on either side of the filling towards the center. Take the point farthest from you and fold it over the filling tightly. Dip your index finger in a little water and trace the edge of the point closest to you. Roll the spring roll towards yourself as you would a burrito. Set the finished spring roll aside and repeat with the remaining sheets.
When the spring rolls are all rolled, heat the oil in a large heavy bottom pot until it reaches 350° F. Add 4-5 spring rolls to the oil and fry until golden, about 6 minutes. Transfer the spring rolls to a plate lined with paper towel. Repeat with the remaining spring rolls.
Place the finished spring rolls on a platter with a bowl of the Mango Sweet Chili Sauce for dipping. Serve immediately with a round of beers.