Heat oil in a dutch oven over medium-high heat. Lightly sprinkle both sides of beef with Cajun seasoning. Place meat in hot oil, and cook about three minutes per side. Saute the onion alongside the meat at the same time.
Pour beef broth and wine over meat and onions. Chop chard, separating out most of the stem pieces. Add the stem pieces to the pot, reduce heat to low, and cover. Simmer for about 60 minutes, turning meat once.
Stir chopped leafy greens into the broth. Turn meat once more, and cover. Simmer for 30 minutes longer. Serve over rice or quinoa if desired.
If you want to serve more people, you could double the beef and greens without adding more liquid.