Marinated Skirt (or Flank) Steak With Kiwi Salsa

Giving credit where credit is due, it never would have occurred to me to make kiwi salsa, but when an unsolicited Weight Watchers Magazine (May/June 2018 issue) arrived with our mail, I looked through it for recipe ideas – and there it was. So, this whole recipe is adapted from the magazine.  As usual, when I say “adapted” I mean that I have altered whatever published recipe I am using.

I was aware, vaguely, that processed papaya is used in commercial meat tenderizers, but I had never given it much thought.  The recipe in the magazine mentioned that the enzyme contained in kiwifruit that breaks down protein  is actinidin. It also cautioned that if the marinade is left longer than 20 minutes the protein will be reduced to mush.  They included and exclamation point, so, of course, I paid attention.

So what is going on? I asked myself.  I knew papaya acted as a tenderizer, and so did pineapple, so did they have actinidin also?  And the other, bigger question was, how did all of this work?

I could not resist “further reading” in quotes, and here is the deal – The food we eat is composed of three things and three things only, and they are protein, carbohydrates, and fat. In order to digest each of these, we have specialized enzymes that tackle their digestion.  Protein is digested with the help a protease enzymes, carbohydrates rely on amylase enzymes, and fats on lipase.

So what is actinidin and why does it tenderize meats?  And what is going on with papayas? Again, with “further reading” but also availing myself of my husband’s medical knowledge, I found out that there is not simply one enzyme devoted to each of the triad of nutrients we ingest, but several.  That is to say, protein might be digested with the help of several different protease enzymes, and so for fats and carbohydrates.  Papaya has papain, a cysteine protease, pineapple, bromelain.

Using any of these three fruits to tenderize meat by breaking down the protein now makes sense.  There are chemicals in those fruits which we can identify and safely say, “Yep! they help me digest that big ribeye steak!” for, not only do they tenderize steak, but once in our digestive track, servings of the fruits go right to work breaking down protein into nutrients our bodies can use.  Pretty sweet, as my son would say!

So, now for the good stuff – the recipe.  I have made this marinade and salsa three times, and find it easy, quick, and very satisfying.  Once we used the marinade on sword fish and found that was even more delicious than using it on steak.



  1. 4 kiwifruit, peeled*
  2. 2 tablespoons lime juice*
  3. 1 tablespoon minced garlic
  4. 1 tablespoon Dijon mustard
  5. ¼ teaspoon black pepper
  6. 1 (1 lb) skirt OR flank steak
  7. 1 cup cherry tomatoes, halved
  8. 2 tablespoons chopped red onion
  9. ¼ cup coarsely chopped cilantro
  10. 3 tablespoon olive oil
  11. 1 teaspoon salt
  12. ¼ teaspoon red pepper flakes

*these ingredients are to be divided

 Directions:  You will make a marinade as well as a salsa with the above ingredients.

For the marinade:

  1. Cut TWO of the kiwifruit in thin slices. Mash them with a fork.
  2. In a small bowl, combine the 2 mashed kiwifruit with ONE tablespoon of the lime juice, the minced garlic, the Dijon mustard.
  3. Place the skirt steak (or flank steak) on a plate and smear the marinade back and front.  For a skirt steak, thinner than the flank steak, tenderize the meat for 15 minutes.
  4. For the flank steak, since it is thicker, tenderize the meat for 20 to 25 minutes depending on the thickness of the steak.

For the salsa:

  1. Dice the other TWO kiwifruit.  Add the cherry tomatoes cut in half or quarters, the chopped onion, the cilantro, the rest of the lime juice. Set aside.
  2. Wipe the marinade off the steak, season with the salt & pepper, and grill to desired doneness.
  3. Serve garnished with the kiwi salsa.

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