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

I was lucky enough to be given a Wonderbag a few weeks ago by the folk at Natural Balance, who asked me to review it for this blog. And, goodness: I am just bowled over by this simple, clever, energy-saving South African innovation.

I'd heard of this product before but never actually got my sticky paws on one. When I carried my bag - which looks like a bean bag with a drawstring - inside, I couldn't help but feel sceptical. Although it's a beautiful thing (my bag is covered in gorgeous navy African Shweshwe cloth, like the one below left), 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, at the Natural Balance Wonderbag Project. Impressively, 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 electricty. 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 has reached boiling point, you clamp on a tight-fitting lid and transfer it immediately to the bag. A little cushion fits snugly on top, and a sturdy drawstring pulls up the edges of the bag forming 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, lukewarm or half-eaten pot in the bag, because bacteria will burst forth and multiply. (With one exception: the Wonderbag is apparently ideal for making yoghurt, and I should imagine that it would do very nicely to hold a delicate hollandaise or béarnaise sauce at the correct temperature for up to an hour.)

Third, you will get best results if your pot is full (choose the correct size pot for the amount of ingredients). 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.

I'll be sharing some of my Wonderbag creations with you in the next few weeks, but in the meantime here is a quick beef chilli I made for the kids last night. I will never make chili 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. (Incidentally, it was this very dish that persuaded my teens to start loving salad when they were kids. )

Chilli Beef Tacos

2 T (30 ml) vegetable oil
1 large onion, finely chopped
1 red or green pepper (capsicum), chopped
1 kg lean minced (ground) beef
3 cloves garlic, finely chopped
1 tin chopped Italian tomatoes or tomato-and-onion mix
2 T (30 ml) tomato paste
1 and 1/2 t (7.5 ml) fresh powdered cumin
1 t (5 ml) red chilli powder [optional]
1 t (5 ml) dried oregano
salt and freshly milled black pepper
1 tin beans and their liquid (kidney beans, baked beans or butter beans will all do)

Heat some oil in a metal pot. On a high heat, brown the minced beef, in batches. Remove and set aside. (Browning the beef isn't essential - see my notes here - but it does add depth of flavour.) Add a little more oil to the pot, turn the heat to medium and add the onion and pepper. Fry until softened; about 4 minutes. Put the mince back into the pot and add all the remaining ingredients, except for the beans. The liquid should just cover the mince; if there is not enough liquid, add a little water, wine or stock.

Bring to the boil and cook at a brisk bubble for five minutes. Stir in the beans and their liquid and bring back to a vigorous boil. Open the Wonderbag and place it next to the hob. Now put a tight-fitting lid on the pot and immediately transfer to the bag. Cover snugly with the cushion, draw the string up tightly and tie a secure bow. (If you don't have a Wonderbag, turn down the heat and simmer for two hours).

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 El Paso 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.