steak sandwich

Steak Sandwich with Red Onion & Mustard Mayonnaise

This steak sandwich is a great quick & easy lunch. It combines, ciabatta bread, mustard mayonnaise, spinach leaves & pan-fried Sirloin steak!

So I fancied something simple and tasty for lunch and thought back to when me and Becky initially met (10+years ago). We used to go into town and at the time, we were young-ish and hadn’t really experimented with dining out. We used to go shopping and then pop into this nice little french bistro. I always used to have the steak sandwich and fries, then off we’d go for a bit more shopping.

Turns out that the little french bistro was actually part of one of the largest branded restaurant chains in the country. Not that it wasn’t good, but we now like to explore a bit more with places to eat. No offense to any branded restaurants out there. Hopefully, they get through this period of uncertainty for the hospitality industry!

Steak Sandwich…

We got all of the ingredients for this sandwich from Waitrose and I can honestly say the bread was great. For me, the bread makes the sandwich and if it’s not good, it ruins it. We usually get our loaves of bread from a local bakery, but these were great to stick in the oven whilst we prepared everything else.

Sirlion Steak

The Sirloin steak was also from Waitrose and it weighed around 200g. I cooked it for around 2/3 minutes each side then left it to rest. I didn’t want it too bloody for a sandwich and it was still nice and tender. I hate when you take a bite and you pull half of the steak out because it’s too tough – no thanks.

frying up the onions

Other Additions…

We made our mustard mayo really quickly by combining standard mayo, some dijon and wholegrain. We smeared this on the ciabatta instead of butter and it gave it a lovely sweet kick. The addition of spinach was an afterthought. It needed a little green to freshen it up but you could easily use rocket etc.

The red onions were cooked slowly on low heat alongside everything else and tasted great. I think they taste great alongside the steak and the mustard mayonnaise. On the whole, pretty much ready in 15 minutes, and filled me up for the whole day.

Yield: 2

Steak Sandwich

steak sandwich

This steak sandwich is a great quick & easy lunch. It combines, ciabatta bread, mustard mayonnaise, spinach leaves & pan-fried Sirloin steak!

Prep Time 5 minutes
Cook Time 15 minutes
Total Time 20 minutes


  • 2 Sirloin Steaks
  • 2 Ciabatta Rolls
  • 2 Red Onion
  • 1 Tablespoon Olive Oil
  • 1.5 Tablespoon Mayonnaise
  • 1/4 Teaspoon Dijon Mustard
  • 1/4 Teaspoon Wholegrain Mustard
  • Handful of Spinach leaves


  1. Heat the oven to 180C and warm the roll through for around 10 minutes. This should give you enough time to cook the other elements.
  2. Heat a tbsp of olive oil in a pan on low heat. Slowly cook the onions, stirring constantly so they cook evenly.
  3. Drizzle and pat olive oil onto your steak. Season with salt and pepper, then in a large iron skillet, bring to a high-heat and cook for 2-3 minutes each side. Once cooked, allow to rest whilst you finish your onions and make your mustard mayonnaise.
  4. Combine your mayonnaise, dijon and wholegrain mustard in a pot and mix well.
  5. Once the Ciabtatta is cooked, take this out the oven and smear on the mustard mayo.
  6. Layer with washed spinach leaves, then slice your steak and add this to the sandwich.
  7. Finish with the cooked onions on top. They should have cooked to a lovely soft, caramelized texture!

Nutrition Information:



Serving Size:


Amount Per Serving: Calories: 603Total Fat: 30gSaturated Fat: 8gTrans Fat: 0gUnsaturated Fat: 19gCholesterol: 83mgSodium: 562mgCarbohydrates: 51gFiber: 4gSugar: 9gProtein: 32g

This data was provided and calculated by Nutritionix on 6/17/2020

I hope you like this quick and easy sandwich for lunch. It was super easy and very tasty and would go great with the addition of fries.

Have a look at some of the other things we’ve been making recently!

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