Melt the butter in a medium size frying pan.
Add the onions, tomatoes, bell pepper, garlic, achiote, and cumin. Cook for 10 minutes over medium low heat, stirring occasionally.
Mix in the shredded turkey and stir well.
Add the turkey gravy and balsamic vinegar; continue cooking over low heat for another 5 minutes.
Let the turkey filling cool down, and then add in the chopped oregano.
To assemble the empanadas spoon the turkey mixture on to the center of the each empanada disc.
Brush the edges of the empanada discs with the egg whites, you can also use water but the egg white acts as a natural “glue” that helps seal the empanada.
Fold the empanada disc and seal the edges gently with your fingers, twist and fold the edges of the empanadas with your fingers. To seal the edges further you can use a fork to press down and finish sealing the empanadas.
Let the empanadas rest in the refrigerator for at least 30 minutes or until ready to bake, this will help them seal better and prevent leaks.
Lightly brush the top of the empanadas with the egg yolk; this will give them a nice golden glow when they bake.
Pre-heat the oven to 400 F and bake for 20-25 minutes or until golden, exact time will depend on the size of the empanadas and your oven.