Preheat the oven to 425 degrees. Meanwhile, brown the turkey or crumbles in a nonstick skillet over medium heat.

While the turkey is cooking, season it with the chili powder and cumin (if using meatless crumbles, add the spices with the corn and beans). Drain, if necessary (if using turkey), remove it from the heat, and let it cool for a few minutes.

Spray a large baking sheet with nonstick cooking spray or line it with parchment paper.

In a medium mixing bowl, combine the corn, beans, chili powder, cumin, salsa, the turkey and the cheese. (The filling can be made in advance and refrigerated for up to 2 days.)

Lay an egg roll wrapper on a flat surface with one of the corners facing you, and, using a pastry brush, brush the opposite corner with egg. Put about 1/3 cup of the mixture in the center of the wrapper, fold the corner nearest to you over the filling, fold in the sides, and roll the wrapper up toward the corner with the egg. Lay the roll on the baking sheet with the seam facing down to hold it together. Repeat with the remaining wrappers.

Spray the top of the rolls lightly with the spray, and bake them for 15 – 25 minutes until they are deep golden brown. Let them cool for 10 minutes or so before serving, and top them with the sour cream, if desired.