How to Make delicious Crock Pot Flat Iron Steak with Portobello Mushrooms & Potatoes! This dinner cooks low and slow and turns a tough steak into melt-in-your=mouth perfection!

Flat Iron Steak
Flat Iron Steak

Easy Flat Iron Steak Recipe

It snowed this week and while you may think that’s nothing, to me it was Mother Nature (or the Alberta weather) letting us know that she ain’t done with us yet. Oh, we may have had the mildest winter that I can ever remember, with very little snow and days so nice that I’ve lived in a sweater instead of a winter coat for weeks upon end, but it’s not over until Mother Nature says so. And she usually says so right after she dumps a large amount of  snow on us for the May long weekend.

We’re still quite a few weeks away from May long weekend, so as much as I had enjoyed my BBQ (and the snow-free deck that it sits on) it’s STILL crock pot weather. It’s still the comforting, hot-food-that-cooks-all-day time of year, so I thought I’d try crock pot flat iron steak.

 Crockpot Flat Iron Steak with Portobello Mushrooms & Potatoes from @kitchenmagpieWhat is Flat Iron Steak?

Flat iron steak is a cut of beef that comes right off of the shoulder-blade area of the cow. This thin strip of steak is a tender, lovely piece of beef that I prefer to cook low and slow, contrary to popular use. The flat iron has come back in style lately, with a lot of restaurants serving it up along with flank and hanger steaks. Sadly, it’s very hard to get one properly cooked and sliced. I am getting cranky in my old age and to be honest, there are very few cuts of steak that I enjoy as a grilled item anymore. I know. Forty is when the descent into senior-ism starts.

However I am completely serious, all jokes aside. Trendy or not, I’ll take a tenderloin for the BBQ and skip everything else. That sounds really hoity-toity (have I ever used that phrase here? Well, it’s about time I did) but for the very few times we that actually eat steak, it’s not that bad.  Go for small portioned, good quality steak for grilling every time and you will be a happy griller.

Flat iron steak does not have to be fancy. It doesn’t always need a chimichurri – although it really is my favorite way to eat flank steak- and it doesn’t need 11 herbs and spices.

I stopped by ACME Meat Market here in Edmonton, the perfect place to pick up cuts of meat that you won’t find at your regular grocery store. You can see with the meat how it will be better when you cook it low and slow. See all that fat marbling?

Crockpot Flat Iron Steak with Portobello Mushrooms & Potatoes from @kitchenmagpie

How to Cook Flat Iron Steak

This was the simplest recipe that I could possibly think of and it is scrumptious. Crock pot Flat Iron steak is SO the way to go!It will dissolve with the right amount of cooking time, leaving you with meat reminiscent of short ribs. Falls apart and into your mouth. Low and slow is meant for the slow cooker, and so are large chunks of onion and massive portobello mushroom along with the flat iron steak.

  • Place the ingredients into the crock pot in the correct order
  • Cook the flat iron steak low and slow for hours
  • Serve and enjoy

Crockpot Flat Iron Steak with Portobello Mushrooms & Potatoes from @kitchenmagpie

The flat iron steak cooks the best when it is placed under the vegetables and cooks with lots of liquid from the beef broth and the vegetables on top that are releasing liquid as well.

Crockpot Flat Iron Steak with Portobello Mushrooms & Potatoes from @kitchenmagpie

This right here?

Dinner perfection.
 Crockpot Flat Iron Steak with Portobello Mushrooms & Potatoes from @kitchenmagpie

It’s such a comforting dish, with simple yet delicious flavours, which is my favorite kind of meal. Prep it, set it, let it cook all day and then come home to a hot, delicious meal ready to go.

Happy Cooking everyone! How’s the weather been where you live? How was your winter?

Love you more than chocolate,


PIN This Recipe to Your DINNER IDEAS or CROCK POT Boards  AND  Remember to FOLLOW ME ON PINTEREST!

Crock Pot Flat Iron Steak with Portobello Mushrooms and Potatoes
Prep Time
10 mins
Cook Time
8 hrs
Easy and delicious flat iron steak done in the slow cooker with portobello mushrooms and potatoes, 
Course: Main Course
Cuisine: American
Keyword: flat iron steak
Servings: 4
Calories: 436 kcal
Author: Karlynn Johnston
  • 2-3 lbs of flat iron steak
  • 1 lb of sliced portobello mushrooms
  • 1 cup beef broth
  • 1 large white onion sliced into large rings
  • 3-4 large red potatoes washed and chopped into 1 pieces with skin still on
  • butter for greasing crockpot
  1. Grease the interior of your crockpot with a generous amount of butter.
  2. Place the flat iron in the bottom of the crockpot.
  3. Place the vegetables on top, then pour the beef broth over the top.

  4. Cook on low for 6-8 hours, until the potatoes are tender.
  5. Serve and enjoy!
Nutrition Facts
Crock Pot Flat Iron Steak with Portobello Mushrooms and Potatoes
Amount Per Serving
Calories 436 Calories from Fat 216
% Daily Value*
Total Fat 24g 37%
Saturated Fat 9g 45%
Cholesterol 149mg 50%
Sodium 180mg 8%
Potassium 1153mg 33%
Total Carbohydrates 7g 2%
Dietary Fiber 1g 4%
Sugars 4g
Protein 45g 90%
Vitamin C 2.5%
Calcium 2.3%
Iron 32%
* Percent Daily Values are based on a 2000 calorie diet.

Hey guys, I'm Karlynn! Welcome to The Kitchen Magpie, my website full of family friendly recipes, cocktails & homesteading tales of chickens & cows from the family farm! Make sure to check out my bestselling cookbook, Flapper Pie & a Blue Prairie Sky ,stay tuned for info on my second cookbook!


  1. Richard Huckle Reply

    Your Flat Iron steak recipe via slow cooker/crock-pot is perfect now that I have found a supplier of this type of steak cut at Morrisons in the UK.
    Much appreciated !

    • The Kitchen Magpie Reply

      Sophie Nakoneczny as long as it’s a steak that has marbled fat or does well when cooked a long time (chuck or blade!) you are good to go!

Write A Comment

This site uses Akismet to reduce spam. Learn how your comment data is processed.