Slow-cooking with a wonderful Wonderbag: easy Chilli Beef Tacos

The Wonderbag amazed me.

I am bowled over by the Wonderbag: a simple, brilliant, energy-saving South African innovation.

I'd heard of this product but never managed to get my sticky paws on one. When I carried my bag - which looks like a bean bag with a drawstring - home, I couldn't help but feel sceptical. Although it's a beautiful thing (my bag is covered in gorgeous navy Shweshwe cloth; see left and below), it seemed improbable to me that a polycotton bag stuffed with little polystyrene beads would hold food at a sufficiently high temperature for long periods. How wrong I was.

I was astonished, the first time I used the bag, to discover that the pot handles were so hot (after it had nestled in the bag for a full six hours) that I needed oven gloves to lift it out. What's more, every single dish I've tried in it has turned out perfectly, except for a pot of rice, which I foolishly left in the bag for two hours (oh me of little faith!). When I took it out, it was so overcooked I could have plastered a wall with it. (Instructions for cooking rice, quinoa and pap properly here.)

You can read all about the bag, its incredible energy-saving capacity and its potential to alleviate grinding rural poverty, here.

The Wonderbag is one of Africa’s first projects to be registered with the United Nations Framework Convention on Climate Change (UNFCCC) as a Clean Development Mechanism (CDM) project. In a nutshell, this means that means that for every wonderbag sold, verified carbon offsets will be traded on the international market.

From a cooking point of view, a Wonderbag can do exactly what a conventional slow cooker (or very low oven) can do, but it uses a fraction of the electricity. There are two stages to cooking a meal in a Wonderbag: first, you bring your pot of food to the boil on a conventional hot plate or hob. When it reaches boiling point, you clamp on a tight-fitting lid, let it simmer for a few more minutes, then transfer it immediately to the bag. A little cushion fits snugly on top, and a sturdy drawstring pulls up the edges of the bag to form a perfectly insulated container. The contents of the pot remain at a whisper below boiling point for hour after hour, making the bag perfect for slow-cooked stews, curries, soups, casseroles and even potroasts.

Some important tips: if you open the bag before the end of the cooking time, the temperature will drop. If you can't resist the temptation to peek, make sure to bring the contents of the pot back up to a boil before you replace it in the bag.

Second, never put a warm or lukewarm pot in the bag, because bacteria will burst forth and multiply. (With two exceptions: the Wonderbag is ideal for making yoghurt, and I have used it with great success to hold delicate hollandaise and Béarnaise sauces at the correct temperature for up to an hour.)

Third, you will get best results if your pot is almost full (it's vital to choose the correct-sized pot for the amount of ingredients it holds).

Fourth, make sure that there is enough liquid just to cover the ingredients. Finally, it pays to give the bag a gentle shake every hour or so - without opening it - to ensure that the ingredients are well mingled during the cooking process.

Here is a quick beef chilli I made for the kids last night. I will never make chilli or a bolognaise sauce on top of the stove again. You can serve this in tacos, or wraps, or on its own in a bowl, topped with all the lovely crunchy bits. (It was this very dish that persuaded my teens to start loving salad when they were kids.)

Note, 5 August 2013: I've updated and amended this blog post to repair the broken links so they point you to the new Wonderbag site.

Wonderbag Chilli Beef Tacos

3 Tbsp (30 ml) vegetable oil
1 kg lean minced (ground) beef
1 large onion, peeled and finely chopped
1 large red or green pepper (capsicum), chopped
2 Tbsp (30 ml) tomato paste
3 cloves garlic, peeled and finely chopped
1 x 200 g tin chopped Italian tomatoes, or tomato-and-onion mix
½ cup (125 ml) white wine
1½ tsp (7.5 ml) cumin
1 tsp (5 ml) coriander powder
1 tsp (5 ml) red chilli flakes[optional, and to taste]
2 tsp  (10 ml) dried oregano
1 x 200 g tin kidney beans and its liquid
salt and freshly milled black pepper, to taste

Heat 2 tablespoons of oil in a large pot (it needs to be a pot with its own tight-fitting lid). Brown the minced beef, over a high heat, in two or three batches. Tip the cooked beef into a bowl and set aside. Add the remaining tablespoon of oil to the pot, turn the heat down to medium, add the onion and pepper and fry until just softened (about 4 minutes). Stir in the tomato paste and garlic and cook for exactly one more minute, without allowing the garlic to brown.  Return the beef mince to the pot and add in all the remaining ingredients.

The liquid should just cover the mince; if there is not enough liquid, add a little water, wine or stock.

Bring to the boil, cover with a tight-fitting lid and cook at over a medium flame for about 4 minutes, or until the pot is very hot and puffs of steam are escaping from under the lid. (The lid should feel very hot to the touch - too hot for you to place your hand on it - before you proceed with the next step.)

Open the Wonderbag, remove the cushion and place the bag next to the hob. Transfer the pot to the bag and immediately cover it with its cushion. Draw the string up tightly and tie a secure bow.

Leave the pot in the Wonderbag for at least two hours, without opening the bag. This mixture is lovely after four hours, and heavenly after eight.

Serve with taco shells, sour cream (or Greek yoghurt whisked with lemon juice, a clove of crushed fresh garlic and a few tablespoons of mayonnaise), grated cheese, avocado, chopped tomatoes, cucumber and coriander, and a shower of shredded lettuce.

Serves 4-6

Wonderbag picture courtesy of Natural Balance.

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