Sprinkle chicken liberally with taco seasoning.

Heat oil in a skillet over medium heat. Add seasoned chicken and saute until no longer pink in the center and the juices run clear, 8 to 10 minutes. Remove from the skillet and allow to cool.

Preheat the oven to 350 degrees F (175 degrees C).

Add onion to the same skillet and saute until soft and translucent, 5 to 7 minutes. Transfer to a blender and add 1 can diced tomatoes with liquid, diced green chile peppers, garlic, cumin, salt, and pepper. Blend until sauce is smooth.

Dice cooled chicken and transfer to a bowl. Drain remaining can of diced tomatoes; discard liquid and add tomatoes to the chicken.

Place about 1/4 cup chicken mixture in the middle of a tortilla. Add 2 tablespoons shredded cheese, then roll tortilla up. Place seam-side down in a baking pan. Repeat to make remaining enchiladas.

Cover enchiladas with sauce and spread remaining cheese over top. Cover the pan with aluminum foil.

Bake in the preheated oven until hot and bubbly, about 30 minutes.