Triple S Farms Round Steak with Guinness and Onions

1 ½ lbs round steak
Salt and pepper
¼ cup vegetable oil
2 large onions, sliced 1/8" thick
2 tablespoons tomato paste
1 tablespoon dark brown sugar
1 can Guinness beer
1 ½ cups beef stock
1 tablespoon Dijon mustard
1 tablespoon Balsamic vinegar
Chopped parsley

Season steak with salt and pepper. Sear meat on both sides in very hot oil in a large skillet.
Remove meat, add onions and caramelize. Add tomato paste, cook for a few minutes, add brown sugar and stir. Add the beer and reduce by ½.
Add the stock, mustard and vinegar.
Return the meat to the skillet. The liquid should come halfway up the sides of the steak - if not, add more stock.
Bring to a simmer, cover, and braise in a 300 degree oven until tender (about 1 ½ hours).
To serve, sprinkle with chopped parsley.