Season the steak with salt and pepper.
In a large bowl, mix the flour, garlic powder, and coriander. Lightly coat the steaks in the flour mix.
Melt the butter in a heavy-based skillet over MED-HIGH heat. Cook the cube steaks in the skillet for 2 minutes on each side, then remove.
In the same pan, sauté the sliced red onions, crushed garlic, and the sliced mushrooms for 5–8 minutes, until soft.
Meanwhile, make a slurry by mixing the cornstarch and water in a small bowl. Pour the mushroom soup and cornstarch mixture into the pan along with the vegetables. Stir to combine over LOW heat. Let the mixture simmer, stirring for about 5 minutes, until it thickens.
Immerse the steaks in the gravy. Cook for another 10 minutes.
Sprinkle the chopped parsley over the smothered steaks and serve. Enjoy!