I've recently learned that phytohaemagglutinin is a toxin found in raw beans (particularly kidney beans) and it's harmful to humans. It's difficult to find information on phytohaemagglutinin relating specifically to black beans but be aware that slow cookers don't always reach high enough temperatures to cook the beans safely. Wikipedia states that the toxins can be reduced to safe levels by:
- Boiling unsoaked beans for at least 30 minutes at 100°C (212°F)
- Boiling presoaked beans for 15 minutes at 100°C (212°F)
- Cooking for 2 hours at 80°C (176°F)
- Pressure cooking for 45 minutes at 15 psi
If you're going to cook these beans in a slow cooker I would recommend boiling the beans as described above before slow cooking. The oven cooking method is hot enough to cook these beans safely.
I’ve cooked Nigella's Cuban Black Beans many, many times since the book came out in 2015 because as well as tasting wonderful, they're easy to make and incredibly versatile. Chop a couple of onions, peppers and some garlic; the rest is just assembly. What you do need to do, however, is give these beans time. Either a couple of hours in a low oven or longer in a slow cooker. As a bonus, this is one of the few recipes I’ve come across where the dried beans don’t need to be pre-soaked. One small addition I've included is a tablespoon of chipotle paste. It gives the beans more depth and interest; I usually add at least two tablespoons but this does make them quite spicy so maybe start with a tablespoon.
Although these beans are a great side dish for any Mexican cuisine, I tend to make them as the main event. They make work lunches a treat when paired with rice and yoghurt and of the many meals I take to work and reheat, these beans attract the most compliments. One colleague swears they smell just like Dominos BBQ pizza but I wouldn’t know as I’m more of a Papa John’s woman.
My last batch of beans went into quesadillas along with cheddar cheese and some caramelised garlic yoghurt on the side; it was an absolute joy of a dinner. The garlic yoghurt is also from Simply Nigella and I’ve recently developed a mild obsession with it (see notes).
For years I cooked these beans in the oven as I don’t own a slow cooker but a few weeks ago a colleague kindly lent one to me. To be honest, the beans taste similar to me regardless of how they’ve been cooked as I let them cool first before reheating them, which thickens and intensifies the sauce. When I’ve made the beans in a saucepan that goes in the oven I’ve browned the onions a little before adding the other ingredients. For the slow cooker method the raw ingredients go straight in - the recipe doesn’t mention any browning. After seven hours in the slow cooker I swear I could still taste the tang of raw onion. It wasn’t strong but it was there (a blob of ketchup helped a little). Once the beans cooled and were reheated they tasted like their normal selves but I would definitely recommend browning the onions first, regardless of how you cook them.
To make garlic yoghurt, slice the top off a bulb of garlic (taking the very tips off the cloves and keeping the base intact) then wrap in foil and bake for around 40 minutes in a 200°C (180°C fan) oven (adjust the cooking time to suit the temperature of whatever you’re cooking; you don’t need to be precise). Like Nigella, I don’t turn on my oven just for the purpose of roasting garlic but if I’m cooking something else I’ll often throw in a bulb at the same time. Once the cloves have caramelised to a dark bronze colour, the whole bulb goes into the fridge where it keeps for a week and the squidgy cloves can be added to soups, stews, or, my favourite by quite some way, Greek yoghurt. 400g of Greek yoghurt, a teaspoon of sea salt flakes and 5-6 roasted garlic cloves amounts to a beautiful sauce that reminds me of the yoghurt you get in a really good kebab shop.
- 2 onions, chopped (any colour)
- 6 cloves of garlic, chopped
- 2 peppers, diced (any colour)
- 500g dried black turtle beans
- 1 fresh red chilli, chopped
- 2 tbsp cumin seeds
- 1 tbsp chipotle paste (more if you like spice)
- black pepper
- 2 fresh bay leaves
- 1 litre water
- Slow cooker: Fill a medium saucepan with boiling water and add 500g of dried black beans. Rapidly boil for 30 minutes then drain.
- Brown 2 chopped onions in a pan for around 5-10 minutes then add to a slow cooker along with 6 chopped cloves of garlic, 2 diced peppers, the boiled black beans, a chopped red chilli, 2 tablespoons of cumin seeds, a tablespoon of chipotle paste, a pinch of black pepper, 2 fresh bay leaves and a litre of water.
- Cook for 6-8 hours until the beans are soft then add salt to taste.
- Leave to stand for half an hour or, if you can, allow to cool then reheat to eat.
- Oven: Preheat your oven to 150°C (130°C fan).
- Brown 2 chopped onions and 6 chopped cloves of garlic for around 5-10 minutes in a lidded saucepan that will fit into your oven. Add 2 diced peppers, 500g dried black beans, a chopped red chilli, 2 tablespoons of cumin seeds, a tablespoon of chipotle paste, a pinch of black pepper and 2 fresh bay leaves to the pan. Add enough water to cover the ingredients by 3cm then clamp the lid on the pan and place in the oven for 2 hours.
- If you can, check on the beans half way through, giving them a stir and adding more water if the level has fallen below the beans, but you can just leave them to cook and they should be fine.
- When the beans are cooked, salt to taste then leave to stand for half an hour or, if you can, allow to cool then reheat to eat.