First of all, the steak has to be deepfrozen.
Then, turn your oven on. I would've put it at around 158 degrees fahrenheit(70 Celsius), because I think the end result becomes better the longer time it takes.
Atleast no higher than 185 (85 Celsius).
When the oven has reached the temperature defined above, insert the deepfrozen steak of in the lower parts of the oven.
No covering in alufoil or anything.
If possible dont use hotair function.
Pure naked, unsalted and frozen meat.
And then, its time to make the brine!
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Brine recipie:
For a 2.5 lbs (1.2 kg) steak its common to use:
33 fluid ounces (1 liter) of water
10% salt (of 33 fluid ounces)
5 - 7 % sugar ( -- " --)
10 - 20 pcs of juniper berries
1 teaspoon of thyme
Black and/or white/green peppers after personal taste
Give it a good boil up and just let it rest while the steak is slowly cooking.
Worth mentioning is, that since the steak is not salted or spiced or anything before going into the oven, the brine is really where you can "do magic". Personally I like to add bay leafs, sometimes fresh garlic and sometimes other stuff, but that is a matter that is easy to understand and adjust after personal preference, I think.
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Back to the still frozen steak in the oven!
Since the steak is deeply frozen and in a oven on low temperature, this is gonna take quite some time. About 7 until 15 hours, all depending on the size of the steak and the oven.
Personally, I think its finished when its core temperature has reached about 140 - 149 fahrenheit. But that is because I like it red, and opinions may differ
Because its frozen, its impossible to insert a meat thermometer, but after 3 - 5 hours its easy to "slide it in" carefully.
Just keep an eye on the thermometer, and remove the steak when it has reached your prefered core temperature.
Then IMMEDIATLEY put it in the brine, meat still hot, brine can be icecold, and let it rest for 5-6 hours in the brine.
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Then remove the steak from the brine, wipe it dry with some household tissue or similar, cut very thin slices and enjoy!
I prefer to eat it with potato gratin, or just boiled potatoes, or just on a sandwich or ..
A few other good companions to this steak is jelly made out of black currant, "tubular lingonberries", ofcourse fried chanterelles and/or a creamy sauce of any kind.