In a medium bowl, stir together leftover turkey, stuffing/potatoes, and vegetables, if you want them mixed in. You can alternatively set your vegetables in the center of each wrapper for more even distribution.
Spoon about 1/4 cup of filling mixture into the center of each wrapper. If you didn't mix the veggies in, you'll use just a little less than a 1/4 cup per wrapper to make 12.
To roll, fold the bottom corner over the filling, then the left and right corners. Roll it up tightly until there is just a flap. With a pastry brush, brush flap with egg whites, and finish rolling it up. Make sure the flap has been sealed down to the roll tightly.
In a cast-iron pan, heat the vegetable oil until a small sliver of wrapper sizzles in it (350°F if you're using a thermometer). Fry 2 to 3 egg rolls at a time, turning to ensure even browning. Do not crowd the pan. Once they're a nice golden brown all around, remove to a paper towel to drain excess oil.
For cranberry sauce, in a small saucepan, combine leftover cranberry sauce, vinegar, and sugar, and simmer for at least 10 minutes to dissolve the sugar.
Warm the gravy in the microwave. Serve both sauces in dipping bowls to share.