Go Back
+ servings
Steak Sandwich with Onions, Mushrooms and Havarti
Print Pin
5 from 1 vote

Steak Sandwich with Onions, Mushrooms, Havarti & Avocado

Prep Time 25 minutes
Cook Time 20 minutes
Total Time 45 minutes
Servings 6 - 8
Author Cooks with Cocktails


  • 1 large flank steak
  • 3/4 cup soya sauce
  • 1/4 cup citrus juice (I have used orange juice,pineapple juice and a mixture of citrus juice)
  • 4-5 clove of garlic (chopped finely)
  • 1 tbsp of grated ginger
  • 3 tbsp brown sugarFOR THE CARAMELIZED ONIONS
  • 1 tbsp olive oil or butter
  • 1 large onion , sliced
  • 1 tsp saltFOR EACH SANDWICH
  • 1 bun (we used ciabatta buns)
  • 1/2 cup sliced flank steak
  • 1/4 cup caramelized onions
  • 1 big slice of havarti cheese
  • 1 tbsp mayo (or a little more or less depending on your tastes)
  • 1 tbsp mustard (or a little more or less depending on your tastes)


  • flank steak recipe, carmalized onion and mustard mixed with mayo
  • Place the marinade ingredients in a ziplock bag and marinate the flank steak at least 4-5 hour or overnight is best.
  • While the steak is marinating, make your caramelized onions. Heat a pan on medium-low heat, add the oil or butter, your sliced onions and sprinkle with the salt. Cook for 8 - 10 mins or until the onions get nice and browned and sweet. Stir every couple mins. Be careful not to burn them. Set them aside to cool.
  • When you are ready to cook your steak, heat your barbecue to medium-high heat. Wait for it to get nice and hot. So you can't hold your hand over the grill for more than a second.
  • Throw your steak on the grill and cook for 4 mins. Then turn slightly, a quarter turn, and cook for another 4 mins. This will get you beautiful criss-cross char marks on your steak. Then turn it over and do the same on the other side.
  • Take the steak off the grill and tent (cover) it with foil for at least 5 mins or up to 10 to let it rest and the juices redistribute.
  • With a sharp knife, slice the steak in thin slices against the grain.
  • When you are ready to make your sandwiches, put your oven on broil.
  • Make your sandwich by brushing the bottom of the bun with a little mayo (optional) then piling the steak on top, followed by the onions and the cheese on top of it all. Place the bottom halves on a tray and put them under the broiler for a couple mins until the cheese is all melted.
  • Spoon some mustard and mayo on the top half of the bun and place it on top of the melted cheese.
  • Serve!