A glass of the same red wine used in the gravy pairs seamlessly, heightening the rich flavors of the dish.
Mix ground beef, parsley, scallion, salt, and pepper. Divide into four even portions and shape into 3/4"-1" thick oval patties, roughly the size of hamburgers.
Place some flour in a shallow dish. Dredge each beef patty, reserving any remaining flour. This will thicken the gravy later.
In a skillet, heat oil and butter. Sauté beef patties for 3 minutes each side until browned but not fully cooked. Transfer to a plate and cover with foil.
Keep the side dishes simple, given the French onion gravy is quite rich.
Add onions and sauté 5 minutes, scraping up the fond or 'brown bits' in the bottom of the pan as the onions cook down.
Add tomato paste to the onions and sauté until the paste begins to brown and even burn slightly. Keep it moving around the pan, scraping and stirring to avoid burning altogether.
Sprinkle onions with reserved flour and cook for 1 minute. Stir in the wine and scrape the fond. Add Kosher salt if desired.
To prepare the cheese toasts, combine butter, garlic, and Parmesan and spread it on one side of each slice of bread. Sprinkle the shredded Swiss evenly over the butter and bake.