A discovery: how to cook beef topside & fillet in a wonderful Wonderbag

It's taken several months of experimentation to write this blogpost, because I wanted to test the method over and again so it works perfectly for you every time. In a nutshell: you can use the Wonderbag, a brilliant energy-saving South African innovation, to produce tender beef topside (and fillet) that's uniformly pink within, dark and caramelised on the outside, and filled with flavoursome juiciness.

 How to cook perfect rare & juicy beef topside in a Wonderbag. The 18th-century
silver mustard pot in this pic was a gift from my husband on our 25th anniversary.

Wine recommendation from Michael Oliver. He says: "Zonnebloem Cabernet 2012."
Go to the end of the page for more detail about this wine pairing.

There are several photographs in this blogpost showing my various recipe trials. I hope this post will encourage you to buy or donate a Wonderbag (which you can do here, or at YuppieChef. If you're not in South Africa, click here).  

My hard-working Wonderbag.

If you're a chef in a busy restaurant kitchen, I'd like to suggest that you supplant some of your sous-vide baths with a few of these versatile gadgets.

Let me go back a little. I've owned a Wonderbag since 2009.  It's a bit raggy and saggy and stained after so many years at the coalface, but I still use it several times a week for making slow-cooked family dishes and my foolproof Greek yoghurt. 

It's also brilliant for holding delicate sauces - such as hollandaise and béarnaise - at a constant gentle temperature for many hours.

I take it along to the supermarket when I'm buying ice cream on hot days, and to the local pizza place when I'm collecting take-outs.

My interest in the Wonderbag was rekindled  a few months ago when I met the ebullient Italian chef Luigi Carola, Global Lead Innovation Chef for Unilever, and best known in South Africa as a star of Knorr's cooking adverts*.

Edge-to-edge pinkness, a lovely caramelised crust, and very tender meat

I don't know how Luigi and I got on to the subject of the Wonderbag, but once we did, over a few glasses of wine, there was much high-fiving.  He told me he'd been experimenting with cooking a variety of dishes in his Wonderbag, and that he was so enthused by this cooking method that he'd written a cookbook on the subject.

What interested me most was his claim that the best fillet steak he'd ever eaten came out of a Wonderbag. Also, said Luigi, many other slow-cooked dishes can be incubated with great success using this method. He told me about Italian relatives who create gorgeous stews, pack them in a Wonderbag, then drive for many hours across Europe to deliver piping-hot meals to homesick children in other countries.

Here's how a Wonderbag works: it has extraordinary insulating properties that prevent heat from escaping from a very hot pot. If you closely follow the steps I've detailed below, the bag will 'hold' your food at a notch below boiling point for several hours.

After that, the temperature inside the bag (and pot) will drop in grudging increments over many long hours. I can't give you exact temperatures using my cheffy temperature probe, because a big no-no of cooking in a Wonderbag is opening it up, but my experience is that when I open my bag after 3 hours, the lid and handles of the pot are still too hot to touch with bare hands.

I've cut off the top of this piece of beef topside to show you what
you can expect when you when you cook it in a Wonderbag.

This slow, even cooking is what makes this technique so effective.

So I set about experimenting with beef roasts.

I adore topside, because my mum has always had a knack of roasting this temperamental cut to rosy-pink perfection.  Perfect fillet steak was my next challenge.

The biggest benefit of cooking beef this way is that you cannot over-cook it.  I can't emphasise enough this huge advantage of using a Wonderbag - you can leave topside or fillet in the bag for two or three hours, or longer, and when you open it up it will be beautifully warm, brown on the outside, and an edge-to-edge blushing pink on the inside.

It will also be well rested, tender and juicy.

There are two more reasons I love this technique.  One, it's so convenient: pop your roast in the Wonderbag and go forth to enjoy your Sunday morning.  Two, it's a huge energy saver. Sure, you'll use up a bit of power as you do the initial browning of the meat, but after that you can tuck the meat in its bag and let its residual heat do the rest of the work.

A whole fillet steak beautifully tender and rosy after two hours in my Wonderbag. 

How to cook topside & fillet in a Wonderbag - two recipes

1. Topside in a Wonderbag

1 x 1.8 kg mature good-quality topside, at room temperature
2 Tbsp (30 ml) olive oil
milled black pepper
a pinch of flaky sea salt
a small sprig of fresh rosemary
1 cup (250 ml) red or white wine
1 cup (250 ml) water or stock
3 cloves garlic, unpeeled and lightly squashed
milled black pepper
a pinch of flaky sea salt

Select a piece of well-matured beef topside. 

Trim any big blobs of fat from your topside. Heat 30 ml oil in a large pot that has a tight-fitting lid, and which will fit neatly into your Wonderbag. Pat the meat dry with kitchen paper and season to taste with salt and pepper. When the oil is very hot - almost on the point of smoking - add the topside and brown it well on all sides, starting with the fattiest side.  This should take about 8 minutes in total.  Turn the topside over with a pair of tongs once each side is beautifully browned and caramelised.

Brown your topside well before you add the liquid. In this experiment
I added finely chopped onions, garlic and crisp bacon bits. Other times,
I've added sliced mushrooms and a pinch of chilli flakes.

Halfway through the browning process, add the rosemary sprig.

Now remove the meat from the pot and set aside on a plate. Drain any excess fat from the pan, then put it back on the heat and deglaze with a cup of wine, scraping and stirring to dislodge any golden residue. Bubble over a furiously high heat for 2 minutes, then add the squashed garlic cloves and water (or stock).

Return the topside to pan, fatty side up, and cover with a tight-fitting lid.  The liquid in the pot should come to about 2 centimetres up the sides of the meat.

Turn down the heat to medium and cook at a fairly brisk bubble for 12 minutes.  If you have a topside smaller than the 1.8kg I've specified in the ingredient list, cook it for 8-10 minutes (you'll have to use your instinct here). Don't take the lid off the pot to check the meat, or the temperature inside will drop.

After 12 minutes, the lid of the pot will be too hot for you to touch with your bare fingers, and you will see little puffs of steam escaping around the rim.

Without opening the pot, place it in the Wonderbag, cover quickly with the cushion, then tightly draw up the strings.  Set aside, undisturbed, for at least 3 hours, or until you're ready to serve it.

If, when you open the bag, you find the beef is too rare - and I've only had this happen once, when I couldn't contain my excitement - you can reheat the pot over a brisk heat until you once again see billows of steam (see above) then place it back in the Wonderbag for another 30 - 60 minutes.

Take the meat out of its pot and set it on a board to cool for a few minutes. Carve into slices and serve immediately.  Or let it cool, then refrigerate and carve it the next day.

If you'd like to make a gravy, strain the pan juices through a fine sieve into a clean saucepan, pressing down with the back of a spoon to extract the the garlic & rosemary flavours.  Boil briskly to reduce to a rich glaze, or thicken with a little flour slaked in water.

2. Fillet Steak in a Wonderbag

1 large whole fillet steak (about 1.5 kg)
a large sprig fresh thyme
2 Tbsp (30 ml) olive oil
3/4 cup (180 ml) red or white wine
3/4 cup (180 ml) water or stock
2 cloves garlic, unpeeled and lightly squashed
milled black pepper
a pinch of flaky sea salt

Two hours before cooking, take the fillet out of the fridge so it can come up to room temperature. Using a sharp knife, trim away any visible fat, then cut away the 'silver skin' (membrane) on the outside of the meat.

Double the thin end over and tie it to the main fillet with kitchen string. Don't worry if one end is much thicker than the other (the thick end will cater for those who like their fillet rare, and the thin, doubled-over end will do for those who like brown beef).

Brown the meat all over as described above - this must take no longer than 5 minutes, in a blistering hot pan. If there is no smoke in your kitchen, your pan is not hot enough!

Halfway through the browning process, add the thyme sprig.  Set the fillet aside on a plate and deglaze the pan with the wine, as detailed above.

Now follow the same steps: cook the wine over a high heat for 2 minutes, then add the squashed garlic cloves and water (or stock). Return the fillet to pan and cover with a tight-fitting lid.  The liquid in the pot should come to about 1½ centimetres up the sides of the fillet.

Turn down the heat to medium and cook for 6 minutes. Don't take the lid off the pot to check the meat, or the temperature inside will drop.

After 6 minutes, the lid of the pot will be too hot for you to touch with your bare fingers, and you will see little puffs of steam escaping around the rim.

Without opening the pot, place it in the Wonderbag, cover quickly with the cushion, then tightly draw up the strings.  Set aside, undisturbed, for at least 2 hours, or longer (see my notes above).

Let the fillet cool on a plate, then slice and serve.

Wine pairing by Michael Olivier: 

Zonnebloem Cabernet 2012

It looks like: A brilliant gem-like deep ruby with an enchanting purple garnet at the edges.  This will change to a more brick red as the wine matures.

It smells like: Blackcurrants, hedgerow berries, spice and cedar from the oak and a whiff of dark chocolate.

It tastes like: Classical Cabernet red and black berries and cassis.  Soft tannins. Fabulous long aftertaste. A truly underrated wine.


* Note:  I have a professional association with Knorr South Africa.

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