Use 1 Tbsp. cooking oil to sauté chicken until done. Add mushrooms and tomatoes, stir well and set aside.
Beat eggs with Seasoning Mix.
Heat remaining 1 Tbsp. cooking oil, add beaten eggs, and lightly scramble. Lower the heat and pan-fry to form an egg sheet. Place cooked chicken and vegetables on half the egg sheet and sprinkle cheese on top.
Flip over the other half of egg sheet to close omelet. Heat through and serve hot.