Mince or finely chop the prawns. Remember it should have a bite so do not overmince to a paste like texture.
Add the carrots and onions along with the garlic, sugar, pepper and salt. Mix well to combine till you get a uniform consistency.
Mix the flour and water to get a paste like consistency which is to be used for sealing the ends of the pastry.
It is faster if you separate your pastry sheets in advance and store in an air tight container or zip lock bag to prevent drying out. Alternately, you can separate the sheets that you want and then wrap in a damp cloth, removing one at a time.
Place the sheet in a diamond shape (i.e. one pointed end of the sheet towards you as depicted in the picture).
Place a small amount of the filling at the end towards you (do not overload with filling as this tends the roll to break open while frying). Hold the edge and fold over the filling towards the other end and then pull it tightly towards you so that the filling is nestled tightly inside. The tighter the roll, the better will be the shape of your spring roll and also helps it from breaking in the oil.
Fold the other two ends towards each other and roll the whole thing into a cylinder. Seal the end with the flour paste to secure it tightly. Place in an airtight container and cover with lid immediately to prevent drying out.
Repeat the same for all the rolls.
Heat enough oil in a deep pan to deep fry the rolls. To check if the oil is hot enough, insert a chopstick or wooden spoon; if you can notice bubbling around the wooden part, then the temperature is right. Do not over heat the oil as this will burn the rolls outside without cooking the inside prawn meat.
Also, fry only 4-5 rolls at a time in a medium sized pan. Overcrowding leads to a temperature drop which results in soggy rolls.
Fry the rolls in batches and place in a strainer. Remove after a few minutes to a kitchen paper. Avoid stacking up to ensure that the crispness stays longer.
To prepare the dipping sauce, mix together all the ingredients; taste and adjust seasoning accordingly.
Serve on a large platter with the spring rolls, lettuce, mint leaves and dipping sauce so that each person can customize to individual taste preferences.