Heat ½ tablespoon of vegetable oil in a pan and sauté the onions, poblano peppers, and mushrooms until softened.

Remove the vegetables from the pan and set aside.

Add the remaining ½ tablespoon of vegetable oil to the pan and cook the chicken until browned.

Season the chicken with salt, black pepper, cayenne pepper, cumin, chipotle, and Mexican oregano.

Deglaze the pan with 1 or 2 tablespoons of cold water.

Return the cooked vegetables to the pan and mix with the chicken.

Place a large flour tortilla on a clean surface and spoon the chicken and vegetable mixture onto the center of the tortilla.

Sprinkle grated pepper Jack cheese on top of the mixture.

Fold the sides of the tortilla towards the center, then fold the bottom edge up and roll tightly to create a chimichanga.

Brush the seam of the chimichanga with egg white to seal.

Heat 2 tablespoons of vegetable oil in a pan and place the chimichanga seam-side down in the pan.

Cook the chimichanga for a few minutes on each side until golden brown and crispy.

Serve the chimichanga with sour cream, guacamole, and salsa if desired.