Flank Steak Sandwich


I’m really enjoying my Big Green Egg! I’m still learning but I’ve been able to make some tasty food lately. I was in the mood for a sandwich over the weekend with lots of flavor. Flank steak is one of my favorites for sandwiches. Ciabatta rolls, grilled onions and basil pesto would round out the recipe. I had lots of basil growing like crazy in the garden.


There are many combinations to marinate meat. However, there is a science to it. Fat, acid, salt and sugar all play a role in how juicy and flavorful the meat will be.

  • FAT: Olive oil helps to dissolve the seasonings and spread them over the meat evenly.
  • ACID: The Worcestershire sauce, balsamic vinegar and lemon juice helps break down the muscle fibers which tenderizes the meat.
  • SALT: Soy sauce increases the moisture in the meat which helps make it more juicy.
  • SUGAR: Brown sugar helps balance the acid and salt. The meat will caramelize and brown quicker.


I’m not a big fan of marinating meat in plastic. Who knows if the acid in the mixture is affecting the bag. If I have the time, I will us a glass Pyrex dish. However, the meat must be flipped every two hours and there needs to be plenty of liquid to cover it. I did not have the time so I stuck with plastic.

MARINATION TIME: Marinate the meat for up to 12 hours. I cooked mine at the 8 hour mark.

I love the caramelized crust on the outside!


I was shooting for Medium at 145 degrees F. The middle was almost there, with the ends being Medium Well. I set the Big Green Egg to 500 degrees F. and cooked the flank steak 5 minutes on each side using the Cast Iron Plancha Griddle, ridge side up . Then, I let it rest for 10 minutes. Resting allows redistribution of the juices throughout the steak. Cut steak across the grain when serving.

Flank steak is very lean. Keeping the meat within the times below will bring the best results.

  • Medium rare: 135 degrees F.
  • Medium: 145 degrees F.
  • Medium Well: 155 degrees F.

Try my Basil Pesto recipe!!

Great meal to kick off the holiday weekend!

This is one of the best sandwiches I’ve ever made! The combination of marinated steak, grilled onions and basil pesto on a toasted roll is hard to put down.

Flank Steak Sandwich

Marinated flank steak with grilled onions and fresh basil pesto.
Servings 4 sandwiches
Prep Time 10 mins
Cook Time 10 mins
Grill rolls and onions 5 mins
Total Time 25 mins


  • Big Green Egg or other grill
  • Cast Iron Plancha Griddle
  • Whisk
  • Garlic press
  • Medium bowl
  • Plastic bag or glass dish
  • Knife



  • 2 pounds flank steak
  • ½ cup olive oil
  • cup soy sauce reduced sodium
  • ¼ cup balsamic vinegar
  • 2 tablespoons lemon juice
  • 2 tablespoons brown sugar
  • 2 tablespoons Worcestershire sauce
  • 1 tablespoon Dijon mustard
  • 1 tablespoon onion minced
  • 2 cloves garlic minced
  • ¼ teaspoon black pepper
  • ¼ teaspoon oregano


  • 4 rolls ciabatta
  • 4 tablespoons butter
  • 1 onion large slices
  • Basil Pesto



  • Whisk together all marinade ingredients in a medium bowl.
  • Place flank steak in a plastic freezer bag. Pour marinade over steak. Remove air from bag and seal. Massage the bag to move marinade around the meat. Make sure the steak is completely covered with the mixture.
  • Marinate in the refrigerator for 3 – 12 hours. Do not marinate for more that 12 hours.
  • While steaks are marinating, make the basil pesto. See link in the ingredients section for recipe. Pesto may be made the day before.
  • While setting up the EGG or grill, remove steak from the refrigerator to bring up the temperature.
  • Set the EGG for direct cooking at 500ºF/288ºC with the Cast Iron Plancha Griddle, ridge side up.
  • Grill steak for 5 minutes on each side for Medium (145 degrees F.). Use a meat thermometer to check the temperature.
  • Allow steak to rest for 10 minutes. Cut across the grain.
  • Place onions on griddle and cook until desired consistency.
  • Remove griddle and place buttered ciabatta rolls on the EGG grate. Toast each side.


  • Spread basil pesto on both sides of the toasted ciabatta roll. Place flank steak stripes on the bottom half of the roll. Top steak with grilled onions. Add the top of the roll and enjoy!


STORAGE: Store in an air tight container in the refrigerator for up to 5 days. Freeze for up to 2 months.
Course: Main Course
Keyword: basil, Meat, onions, Pesto, Steak

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