Preheat the oven to 350 degrees F. Place a cast iron skillet in the oven.
Pour the beef broth in a saucepan over medium-high heat. Add the green onions, yellow onions, celery salt, garlic and sea salt. Bring the mixture to a hard simmer for about 3 minutes, stirring occasionally.
Stir in the wine and let simmer for about 3 minutes, stirring occasionally.
Meanwhile, melt the butter in a small skillet over medium-high heat. Add the flour and continue stirring until the mixture thickens slightly.
Add the flour mixture to the red wine sauce and cook 3-5 minutes or until the mixture thickens slightly. Remove from the heat and cover.
Rub both sides of the venison steaks generously with salt and pepper.
Remove the cast iron skillet from the oven and place over high heat. Add the oil. Sear the steaks about 1 1/2 to 2 minutes per side.
Reduce the heat to medium and pour the wine sauce over the venison. Cook an additional 3-4 minutes, basting occasionally. Serve warm with additional sauce on top.