Place chicken, spring/green onions, soy sauce, oyster sauce, Chinese wine and stock powder into a bowl. Add the ground white pepper and toss well to combine. Cover and refrigerate for at least 20 minutes but up to 24 hours.
Meanwhile, tear ham into roughly 20 equal pieces and chill until required.
In a small bowl, combine plain flour with just enough water, I used 3 teaspoons, to make a thick paste. Set aside.
Working with one spring roll wrapper at at time, gently seperate from the stack the lay face down, shiny side out, with one of the corners pointing to you.
Place a few slices of chicken (with some spring onion) into the corner closest to you, then top with a piece of ham. Fold the wrapper over to enclose then roll up firmly (not too firmly that it splits though). Just before the end, using your finger, brush a little “flour glue” over the end corner then roll up to fully enclose and seal. Repeat with remaining ingredients until you have 20 rolls. Cover and chill until required.
Heat enough oil in a wok or deep saucepan to come one-third up the sides until it reaches 180℃. Alternately, use an electric deep fryer following the manufacturer’s directions. Tip: To test if the oil is ready, drop a cube of bread into the oil—it should crisp up within 20 seconds. Alternatively, use a laser temperature gadget for accuracy.
First Deep Fry: Working with 4-5 spring rolls at a time, carefully lower them into the hot oil and cook for 4-5 minutes or until they are golden brown and crisp. Use a slotted spoon to remove them, drain on paper towels quickly, and then transfer to a wire rack. Repeat the this process with the remaining spring rolls, ensuring that the oil returns to the correct temperature before frying each batch.
Second Deep Fry: Reheat the oil to 200℃. Do a second fry on the spring rolls, in batches, for 1-2 minutes until golden brown and 100% cooked through (make sure to test one). Drain and set aside.
Serve the Chicken & Ham Spring Rolls with Chinese Sweet & Sour Dipping Sauce or your sauce of choice.