In a shallow bowl combine flour, garlic powder, paprika, onion powder, salt, and black pepper, whisk.
Place a large cast iron skillet over medium-high heat. Add oil and heat it up. Once hot, dredge both sides of cubed steak in the flour mixture and cook 5 minutes per side.
Remove steak from skillet and set aside and cover with foil.
Once done cooking the beef, to the same skillet add onion, broth, and ranch mix. Scrape the bits from the bottom of the pan with a wooden spoon, bring to a simmer and cook until the onion is tender about 3-4 minutes.
Return steak to the pan to warm it up, serve immediately over mashed potatoes.