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Steak, Mozzarella & Caramelised Onion Sando

Steak, Mozzarella & Caramelised Onion Sando

Serves 2 | with 21 Day Aged Rump Steak and Pesto Mayo
4.0(34)
Recipe Development Team
Recipe Development TeamUpdated on April 02, 2026
Calories
773 kcal
Protein
49.6g protein
Total
30 minutes
Difficulty
Easy
Allergens:
  • Wheat
  • Barley
  • Cereals containing gluten
  • Milk
  • Egg
  • Mustard
  • Nuts
  • Cashew nuts
  • Cereals containing gluten
  • Rye
  • May contain traces of allergens
  • Peanut
Produced in a facility that processes eggs, milk, fish, peanuts, sesame, shellfish, soy, tree nuts, and wheat.
serving amount

2 unit(s)

Ciabatta

(Contains: Wheat, Barley, Cereals containing gluten May contain traces of: Cereals containing gluten, Rye)

300 grams

21 Day Aged British Rump Steaks

1 unit(s)

Onion

1 ball(s)

Mozzarella

(Contains: Milk)

32 grams

Mayonnaise

(Contains: Egg, Mustard)

30 grams

Basil Pesto

(Contains: Nuts, Cashew nuts, Milk May contain traces of: Peanut)

20 grams

Wild Rocket

Not included in your delivery

½ tsp

Sugar

Energy (kJ)3235 kJ
Energy (kcal)773 kcal
Fat45.9 g
of which saturates17 g
Carbohydrate48.7 g
of which sugars7.4 g
Dietary Fibre4.7 g
Protein49.6 g
Cholesterol114 mg
Salt2.3 g
Potassium819.2 mg
Calcium54.6 mg
Iron5.1 mg
Always refer to the product label for the most accurate ingredient and allergen information.
Large Frying Pan
Baking Tray
Aluminum Foil
Pan

Instructions

Get Started
1

a) Preheat your oven to 220°C/200°C fan/gas mark 7. Halve the ciabatta.

b) Remove the steaks from your fridge to allow them to come up to room temperature.

c) Halve, peel and thinly slice the onion.

d) Heat a drizzle of oil in a large frying pan on medium heat. Once hot, add the onion, season with salt and pepper and fry, stirring occasionally, until golden, 10-12 mins. 

Caramelise the Onion
2

a) Once the onion has softened, add the sugar (see pantry for amount) and cook until caramelised, 1-2 mins more.

d) Once caramelised, remove the onion from the pan and pop into a small bowl. Keep the pan for the next step.

Fry your Steaks
3

a) Add a drizzle of oil to the (now empty) frying pan and return to high. Season the steaks with salt and pepper. TIP: Rump steaks naturally vary in shape, so adjust the following timings depending on how you like yours cooked.

b) Once very hot, lay the steaks into the pan and fry until browned and medium-rare, about 5 mins. Turn halfway through. TIP: Cook each side for 1 min more if you like it more well done. IMPORTANT: Wash your hands and equipment after handling raw meat. It's safe to eat when browned on the outside.

Prep the Bread and Mozzarella
4

a) Once the steaks have cooked, transfer to a board, cover with foil and allow to rest for a couple of mins.

b) While the steaks rest, drain the mozzarella and squeeze out as much liquid as you can. Pat dry with kitchen paper, then tear into small pieces.

c) Pop the ciabatta into the oven to warm through, 2-3 mins.

Make the Pesto Mayo
5

a) Pop the ciabatta into the oven to warm through, 2-3 mins.

b) Meanwhile, in a small bowl, mix together the mayonnaise and pesto, then season with salt and pepper.

b) Once warmed, spread the pesto mayo over both lids and bases of the ciabatta halves.

c) Once the steaks have rested, cut into bite sized pieces.

Build your Sandwich
6

a) Top each ciabatta base with the caramelised onion, followed by the steak pieces.

b) Arrange the mozzarella on top of the steak and, if you'd like to, pop it back into the oven until the cheese has melted, 2-3 mins.

c) Top the cheese with the rocket, then finish with the ciabatta lids. Share between 2 serving plates to finish. 

Enjoy!

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