Start by spraying a large skillet with non-stick cooking spray and heating to medium-high heat. Once hot, add each cube steak and brown either side of them. Add salt and pepper to each side. Once browned (not cooked all the way through), remove from the skillet and set aside.

In the same skillet, melt half the stick of butter over medium heat. Wait until the butter begins to sizzle, then add in your peppers. Stir to coat with butter and cook for 2 minutes. While the peppers are cooking, cut the steaks into one inch pieces. Mix in the onion with the peppers and add salt, pepper, and red pepper flakes to taste. Cook for another 2 to 3 minutes, then add the cubed steak and mix to combine.

While your vegetables and steak are cooking: Make a rue by melting the other half stick of butter over medium-low heat, in a separate deep pan, and slowly whisking the flour into it until the mixture is thick and paste-like. When this has been achieved, add salt and pepper to taste (maybe a tsp each). Next, reduce to low heat and slowly add the milk to the rue while whisking. Adding the milk too quickly will make the mixture chunky instead of creamy. You may not need the whole cup as this should be thick like gravy. Once the desired consistency has been achieved, add the yellow and Dijon mustard and hot sauce, whisking to combine.

Remove both pans from heat, and strain the liquid out of the bottom of the steak/vegetable mixture. Add 1/4 cup of the gravy to the mixture and toss to combine.

Serve over white rice (if desired), and top with gravy.