Flat Iron Steak with Herb Butter

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Flat Iron Steak with Herb Butter

Flat Iron & Compound Butter Explained

The Flat Iron Steak

The flat iron is cut from the oyster blade after the gristle running through the middle is removed. You’re left with a flat, even slab of beef. For me, you want to give it a bit of a dry brine, even if it's just for 20 minutes before grilling. Salt the steaks heavily on both sides and leave them on a wire rack uncovered for 20 minutes to an hour before cooking. The salt pulls moisture to the surface and then back in, seasoning the meat all the way through.

The Compound Butter

Compound butter is one of the easiest ways to add flavour to a finished steak. You’re just blending softened unsalted butter with whatever flavour you want, here it’s garlic, chives, tarragon and nutmeg, a classic European combination. I always start with unsalted butter so you can control the salt yourself. If you making it just before you cook the steak, keep it out at room temp. Or if you're making it the day before, roll it into a log in cling film and keep it in the fridge or freezer until you need it. When we add the butter over the steak, it will melt and bastes everything in herby, garlicky fat.

Ingredient Notes

Flat iron steak:

You should be able to get it from most butchers and it's likely the most economical cut of steak in there. If they don’t have it, you can buy an oyster blade and break it down or skirt steak works as well.

Unsalted butter:

Use unsalted so you can dial in the salt level yourself, you can always add more but you can’t take it out. Make sure it’s soft before processing or you’ll end up with lumps.

Tarragon:

Fresh tarragon has a soft aniseed note that goes well with beef. Buy it fresh, dried tarragon loses most of its character. If you can’t find it, a mix of dill and parsley will get you a similar flavour.

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Ingredients

400g flat iron steak
Sea salt and cracked black pepper, to season
100g unsalted butter, softened
1 bunch chives
2 cloves garlic
1 tbsp chopped tarragon leaves
¼ tsp freshly grated nutmeg
1 bunch spring onions
2 tbsp olive oil

Equipment

Chopping board
Chef’s knife
Microplane or fine grater
Small food processor
Small bowl
Wire rack and tray
Charcoal BBQ, gas grill or cast iron pan
Tongs
Meat thermometer

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Directions

PREP YOUR STEAK AND GREENS

Trim the flat iron of any sinew, then slice in half into 2 equal sized steaks.
Season well with salt and place on a wire rack over a tray and set aside for 20 minutes up to 1 hour.
Trim the spring onion tops and tails. Drizzle with half the olive oil and season with some salt. Set aside.

MAKE THE BUTTER

Finely grate the garlic and finely slice the chives. Place in a small processor with the butter, tarragon and nutmeg. Season with some salt and pepper and process until well blended.
Transfer to a small bowl and set aside at room temperature.

COOK THE STEAK

Preheat a charcoal grill or BBQ grill to high heat.
Pat the steaks dry and rub with the remaining oil on both sides.
Cook the steaks for 6-7 minutes, turning every minute, until medium rare (pull it off at 48°C/118°F) or cooked to your liking. Add the spring onions to the grill in the last 2 minutes of cooking, turning to char on all sides.

FINISH AND SERVE

Allow the steaks to rest for 2 minutes, then carve against the grain into thin slices.
Place the onions on a serving plate and top with the sliced steak. Dollop with the butter and serve!

Notes

Chef Tips

Carve against the grain

After resting, look at the steak and find which direction the muscle fibres are running, then slice across them, not along. Flat iron has a long, obvious grain. Cutting against it shortens the fibres in each slice and makes the meat noticeably more tender to chew.

Storage

The compound butter keeps in the fridge for 2 weeks or in the freezer for 3 months. Roll it into a log in cling film or baking paper for easy slicing. Cooked steak is best eaten straight away, but leftovers will keep in the fridge for 2 days. Slice cold for sandwiches or warm through gently, reheating in a hot pan will push the doneness too far.

FAQs

Can I cook this without a BBQ?

Yes. A cast iron pan over high heat works really well, you’ll get a great crust. A gas BBQ is fine too, just make sure it’s hot before the steak goes on. The cook time stays the same.

Can I substitute another cut?

If you can’t find flat iron, oyster blade or skirt steak both work with this method and timing. Avoid anything much thicker than 3cm or you’ll need to drop the heat and cook longer.