2 garlic cloves, finely chopped
2 T. grill seasoning
1 t. hot sauce
2 T. Worcestershire sauce
2 T. red wine vinegar
5 T. EVOO
2 lbs. flank steak
2 large yellow onions, thinly sliced
1 T. fresh thyme leaves, chopped
salt
fresh ground pepper
1 C. chicken broth
4 large croissants
4 slices Gruyere or Emmentaler cheese
Heat grill to high heat. Preheat broiler.
In a small bowl, mix the garlic, grill seasoning, hot sauce, Worcestershire sauce, and vinegar. Whisk in about 3 T. EVOO. Place flank steak in a shallow dish and pour marinade over. Toss to coat thoroughly and marinate for 5-10 minutes.
While the steak is marinating, heat a large skillet over medium-high heat with the remaining 2 T. EVOO. Add the onions, thyme, salt and pepper and cook, stirring frequently for 7-8 minutes, until the onions are deep golden brown. Add the chicken stock and continue to cook for 2-3 minutes more until the chicken stock has almost completely cooked away but the onions are still a little wet with the stock. Remove from the heat and reserve.
Remove the flank steak from the marinade and pat dry.
Grill the flank steak for 6-7 minutes on each side. Remove the steak from the grill to a cutting board to rest for about 5 minutes, covered loosely with foil. Thinly slice the flank steak on an angle, against the grain.
Split the croissants in half and arrange on a cookie sheet, cut sides up. Pile some of the onions on the bottom of each croissant. Arrange a pile of the sliced steak on top of the onions and then follow that with some more onions. Place slices of Gruyere or Emmentaler cheese on top and transfer both the croissant bottoms and tops to the broiler. Melt the cheese and toast cut sides of the top, 1-2 minutes. Place the croissant tops on the melted cheese. Serve immediately.